I did some thinking and some more calculating on paper and after talking with DSSTRBD about his ride a little and how Mr. Harris did the narrowing/sectioning and where his rims sit with backspacing at 8 inches, I came up with this.
I will narrow/notch the frame to gain clearance, so that I can run 7 to 7.25 inches of backspacing. Looking more at 7.25 inches backspace. I have a 9C1 axle in my car where as his is an Imp, so if I put his rim (18X12 with 8 inches of backspace) on my car it would sit further in about 3/4 of an inch due to rearend width differences.
So my rims in the rear have +59MM offset which comes out to 8.82 inches of backspace, so to get my ideal(on paper mind you) 7.25 inches of backspace I am going to need an adapter 1.57 inches wide, which is good, I like the idea keeping the spacer/adapter as thin as possible. The calculations work right, but we will have to see on the car once I get everything all mocked up.
For the front, they are 18X9.5 with +40MM offset, which is 6.82 inches of backspacing. Going with about 5.5 inches of backspacing up front need a spacer of 1.32 inches, again sounds good to me. This will all be relative on the type of hub that I decide to use for the Vette brakes as well as the thickness of the rotor hat as well, may have to take it down to 1.1 inches because of this. Not sure, frame first, brakes next, then measure for another set of adapters, mill the 3 inch ones that I have and see what happens.
Somewhat of a game plan.
received two things not related to the wheels and tires today via fedex, Gm part numbers 16519237 and 16519238, can you guess what they are
Funny they are in the original boxes, just crazy. Simple google search will tell you