Hey malibu795 did you wind up going this route?
If not here is what I've found on mine, seems only a few people have done this, at all. I'll start out saying mine are 17x9.5, not 17x9, and the tires are 275/40/17.
17x9.5 is a bust when it comes to lowering spindles. Where the wheel/tire sits in those pics is about the best you'll get, because the location of the tie rod is in the way... this would change with stock spindles because the actual hub location is moved 2" down on the spindle, clearing the tie rod. It's clear that the only way this would work would be if you could stretch the lip of the fender out probably at least 1.5" for clearance, possibly 2". The edge of the tire sidewall is
exactly 1" from the outer lip of the fender.
Next hurdle, backspacing. With stock a-arms, the most you'll get comfortably is 4.875" (4 7/8"), possibly 5" if you're lucky. 4.875" is the backspacing the wheel is at in the pics. If you go tighter (only way would be with stock spindles) you will likely come into contact with the a-arm, frame, or both depending on tire height, which leads to the next topic.
If everything sits properly, the car is 3" lower than stock: 2" Belltech spindles and 1902 Hotchkis springs (1" advertised drop). At this height with 275/40/17s the tire just barely rubs the rear of the inner fender at full lock, possibly worse if the suspension is moving. The tire also contacts the lower 'tip' of the wheel well lip (where the wheel well lip comes down and meets the very bottom of the sheetmetal), so it's possible that would need to be either trimmed or modified somehow for clearance, again just barely.
Do I want to run a set of 275/40/17s on all 4 corners? Yes I do.
Is it an easy job? No it's not. You would need to either modify the suspension - either by running different a-arms with stock spindles for more wheel clearance, or modify the fenders to clear the wider tire with lowering spindles.
Either way it won't be cheap, and to match the wider track you would gain with the front tires + lowering spindles, you would either need to modify the rear fenders as well to match and go with less backspacing on the rear (think about 2" less)... this would give the car more of a 'Trans Am'-ish look, but if done right it would almost be hard to tell by someone who isn't that familiar with a G-Body. To get the front tires to sit in line with the rears (4.875" is just about perfect for a 17x9.5 btw, only light trimming or rolling of the fender lips is all that's required), you would have to go the a-arm/stock spindle route and find some way of making clearance with the inner fenders.
