Another Wheel/tire question. Please help

[Jusio]

I posted in another thread but I thought it would be better to ask in a new thread..
I’m ready to order a set…
I know there are a lot of variables on the measurements on these trucks BUT....
If I keep 6 lug rear drum (original 12bolt--1969) & CPP modular drop spindles/disc up front. Total drop up front 4.5-5” rear 6”
anyone have input or knowledge if this wheel combo would work:

American Racing Rally Wheel
front: 20x8, 0mm offset, 4.5 BS
rear: 20x9.5, 0mm offset, 5.25 BS

Not positive on tires yet. But I did want more sidewall for a better ride if possible.
Maybe 275/50 in the rear?
I don't mind wider wheel tubs if needed.... Didn't want to do spacers if possible.
Like I said, I know its not 100% without measuring actual truck, but was hoping for input and I imagine others have this same setup

Thanks again