My first post was going to be in the intros, but this caught my eye. I had a 66 KGT FB with 15x8's and 225/50/15's. From what I remember, the B.S. could not be more than 4.25", to avoid tie rod end interference. The biggest fender clearance issue was at the front lower corners. Also my fender lips were rolled. This was my "performance upgrade" from 14x7's w/ 225/60's, over 15 years ago. Seemed like a big deal then, but now I read they're fitting 17x8's w/ 245/45's! The tire size seems feasible, but some of the B.S. I'm hearing of are 4.5" or more. Not sure how that's clearing the suspension and steering. Oh yeah, the other problem was tire height. I could not run more than a 25" dia. as the car was lowered by 1". If the tires are not mounted yet, test fit the rim first. The key measurement is the backside spacing.
Good luck,
Rob