Right now my wife is only aware of the upcoming paint/body cost on my '72 - and even that is sketchy. She does not yet know about the true trac rear end I plan, or the upgraded front suspension(!), or the new brake lines, or the refurbished standard gauge pod, etc, etc. It has all been "academic" due to this project being tabled for years due to family priorities. But after years I have the garage/workshop in needed and the main problems are keeping the budget in limits and time to work.
Doing a lot yourself and being very careful to choose the specific performance goals for the car are the only ways I know of to limit the financial impact (as I have a kid about to enter college, this is important). The aftermarket for Mopars is now huge - when I bought mine in '95 there was nowhere near as much. Now you can buy a Hotchkiss suspension or one from Mancini, completely replacing the torsion bars and K member, and the leaf springs, too - all with expensive modern stuff. I love that there is a great new industry for all this, but since I am worried about the cost of just getting the least expensive rotisserie I can find, I will have to leave all that hardware to those who can afford it. Besides, a modern Challenger R/T, used, can be purchased for well under 25K, especially if you are willing to take one with somewhat higher mileage. I have trouble with the disconnect there - spending huge dollars just on upgrades does not seem worth it when I can get a whole modern car for an incredible price - with airbags too. Anyway I am sticking with torsion bars and leaf springs for my car, probably with tubular upper control arms and other parts from Firm Feel. BTW my engine is a rebuilt 318 done by a colleague of mine in the National Guard who briefly raced it in a '69 Cuda before stepping up to a 360. It is bored out .30 over, has Keith Black parts, is blue printed, and I got it for $600. My 4-speed is rebuilt also; I think I spent $250 on the transmission and another $250 to rebuild it - I am not sure I could pull that off today.
Good luck with your project - hopefully you will be on the road sooner than I will.