Engine Bay, Trunk and Floor Pan Prep Questions

[PlumCrazy73Cuda]

Looking for some advice on prepping the floor, engine bay and trunk for paint.
My car, a 1973 Cuda, was dipped about five years ago and a single coat of epoxy primer was applied.
I replaced a few panels, floor pans, trunk pans, patched a few holes, added frame connectors, rad support and cowl reinforcements.
The car is currently on a rotisserie so I have easy access to the bottom of the car.

My main question is what do I need to do to prep the floor (both sides),  trunk floor (both sides) and the engine bay for paint?
What grit should I be using to sand the bare metal and existing epoxy primer so I can shoot two more coats of primer and then paint?
Given all the contours of these areas it looks like I will be doing it all by hand.

I already purchased epoxy primer from Southern Polyurethanes and I am planning on going with a single stage paint for painting these areas and then a BC/CC for the outer shell.
Thanks in advance. This is my first paint job and I want to make sure that I am doing this right the first time.

[AZDAN]

I did just about the same with my 72 except I used an etch primer, i scuffed it up, wipe it down with grease/wax remover then sprayed 2k primer on it. then painted the engine compartment door jambs, trunk, and floor & bottom of the car.

[PlumCrazy73Cuda]

Thanks for the reply.
What did you use to scuff the primer?
Scotchbrite or sandpaper? What grit?

[Cuda Cody]

Scuff the area with 320 or red scotch bright.  Seal with 2 part epoxy.

[ksierens]

  but also wipe it down like AZDAN said.

[PlumCrazy73Cuda]

Thanks for the responses. I really appreciate the input.
Time to get sanding so I can get this thing painted.

[elitecustombody]

Red scuff pad would work much better than sandpaper, because it's a lot more forgiving on edges and corners,plus you can force it into tight areas unlike sandpaper, my