1987 Buick Grand National Pro Touring "Wheels" Help choosing...??

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I ordered and received Ride Tech's Level 2 coil over suspension kit. Some other stuff from Detroit Speed.
The car sits on some BS 20 X 8.5 MHT made Foose nitrious wheels now. "not for long" Which are for sale by the way:





I'm beginning the search into what wheels and tire combo best suites my car and the pro touring driving that i want to do with the car....
So I'm open to learn as much as possible before i make that decision... whats to big of a wheel? whats to small?? what type of width rim/tire should i be shooting to get under there??
Offset info? Anything info will be appreciated.

Just got done doing a "power-master" to "vacuum" brake conversion in my Grand national. I also converted the back drum set up to a disk set up to match the front. All 4 piston and 13" Rotors.
New Master Cylinder, Brake Booster, Vacuum Block

Proportional Valve:

Rear Disks Now:

Master Cylinder and Proportional Valve: