The time has come, the restauration and upgrade will commence next week. 

The plan is to go down the restomod route. First up is to sandblast the undercarriage, anticorrosion coating, new brake lines, new fuel line, 3-point seat belt installation, "new" seats (a pair of excellent buckets seats I have lying around in the garage, much better than the original ones), new water pump, new oil filter, new thermostat, new engine gaskets, new radiator (custom-made aluminum) w/ electric fan(s)...

I am not a mechanic and have zero experience so all the works are going to be done by a friend of mine, a professional mechanic.

Lots of stuff to do for starters and I hope it'll be done by July so I can drive it around during summer time. 

For the next few years I plan to do lots of other upgrades: disc brakes, 18" wheels, QA1/Hotchkis suspension, QA1 K-member, Vintage Air, overdrive etc.

After stripping out the whole interior we realised that there are holes in the floor, both front and back. It seems previous owner started the restoration, but then quit, patched the car for sale (interior was brand new - carpets, vinyl seat covers etc) and that's where I got into the picture...

Interesting thing is that the trunk floor is new and rear floor pans. I had to get AMD's front floor pan halves and rear under-seat floor pan. The work has begun... Rust must go! 

It seems that the roof is in a bad shape and that I might be forced to replace it too. Plan B is to de-rust it, completely protect it with anti-corrosion primer and do the vinyl roof. That way the imperfections will not be visible. Opinions? Ideas? Suggestions? 

Looks can be deceiving... 

Now seriously, it's not so bad, but there are issues all over the car. The worst thing is that they painted in completely on the underside so there was no way to see what is OK, where the filler is and what's bad. It still is a guessing game... The overall condition is more-or-less OK so me and my mechanic decided not to got full resto so it won't be stripped down completely and sandblasted.

As for the stands - my mechanic made them, he is comfortable going under them. 

I don't know if it's an optical illusion or not but in two different photos it looks like your RF wheel is severely rolled in (positive caster)

Beyond that rust repair comes first.... Good Luck....

Since Murphy's laws always work, when the car was taken apart lots of hidden issues came up. Now it is clear that 90% of the car was masked up just for sale. 

Somebody previously started a restoration project and quit at some time, sorted it out to look nice to be sold and that's when I got into picture. The trunk floor pan is new, both left and right rear floor pans, front valance, seats are re-vinyled, new headliner, new carb (Edelbrock, I'm not sure which exact model - maybe somebody could take a look at the photo and try to figure out), new rear spoiler, new gas tank, new exhaust, engine is 440 instead or original 318 and I think the tranny is A727 instead of A904... but the body is pretty rusted out. It's not unsalvageable, but a LOT more work than previously considered.

Anyway, being angry or frustrated won't solve anything so I will live with the idea that it will take me a year or two to get the Challenger back on the road. Everything depends on $$$ of course...

So, one of the major issues is the main console and the metalwork underneath. It seems "they" (whomever "they" might be - either the guy from US who sold the car or the Pedal to the metal muscle car shop where I bought it) put a new dash pad on top of the old one which is in horrible state. The metal core underneath is rusty as hell, firewall too... The cover pad was just glued to the old one, luckily we managed to get it off without breaking it.

The main problems is that there are no AC/ventilation hoses - it was just put together and I had no way of checking when I was buying it. The AC compressor is missing (I saw that when I bought it) and since I figured to install Vintage Air kit it was not a problem for me at that time.

What would be the best thing to do right now? Since it is taken apart and the body is being taken care of regarding all the rust, I need advice for the hoses. If I get the Vintage Air kit does it come with all the new hoses or I have to re-use the old ones? Does anyone have photos of the firewall from the inside of the cabin? Me and my mechanic have no clue what it should look like when it's properly done. Of course, we will sort something out, but I'd rather do it the right way than just to do it. 

BTW, all the electric cables will be replaced. IMO it's better to do everything nut&bolt if possible than to have issues later on.

Tranny - is this A727 or A904? I googled and I think it is 727, but I'd like somebody who knows better to please confirm if possible...

And some photos BEFORE taking it apart...

This is a small thing given the other work ahead of you, but in the picture of the engine bay it looks like your heater core is directly connected to the water pump.    There's supposed to be a control valve mounted on top of the passenger side fender well.    A picture of one is shown below.   Unless you want the heat on all of the time it will need corrected eventually. The tab in the center is tied to the temperature selection lever on the dashboard by a metal cable.

Between the fuel line replacement and the rustproofing work you described, I'm assuming you have or will be dropping the fuel tank.  After it's pumped empty, give a shake and see if it rattles.  I had a bunch of rust scale on the inside of mine that would've plugged any filter downstream, so I ended up getting a new fuel tank.

The discovery work will go on for a while as you get into the car further, leading to more things you didn't know you would need to spend $ or time addressing.   Hang in there.   There are very experienced people here willing to share their knowledge that us first-timers will continue to rely on through our projects.

Good luck!