Doh! my bad, should have said, off the shelf one piece 17x9 5" BS would be for the rears...
I know those fit, same as what's on there now.
The Custom 2 piece 17x8 with custom BS, 5.25, 5.5, 5.75 etc. can be ordered and would be for the fronts.
I'll put the Year One 17x8s back on and measure wheel clearance to the OTR end.
Won't be exact because no front end alignment on the car, everything is just bolted together out of the box.
Eyeballed for everything and the torsion bars cranked up to keep the tires from hitting the fender lips.
It should give me some idea how much further back I can go though.
I'll measure clearance with the standard 11.75" rotors too. I'd be okay with going with the BS to fit the standard rotor and a spacer to use the same wheel with the 73 C-Body rotor...
Measure actual backspace of my 17x8s
Measure clearance to OTR end
17x8 BS + clearance to OTR = new wheel BS
Can always add minimal spacer if I end up too close to the otr after alignment.