70-73 Camaro, what's the widest rims/tires I can use?

[The T-man]

Hello people,
glad I found Lat-G, the cars here are incredible, the time and workmanship that goes into some of the cars amazes me. It's a place I keep coming to for inspiration and help in keeping me motivated on my car.

I have a 73' R/S Camaro, it's dropped 2" rear and 2" spindles in front.
What are the widest rims/ties that will work without major mods? I don't mind minor rolling/trimming.

I'm looking at 18x8 front and 18x10 rear
or 20x9 rear? And backspacing, exact tire sizes please, I'm hoping you guys can save me a few days of trial and error swapping. =)

Any help, pics, advice is greatly appreciated.