Decent handling susp setup?

Oh boy. Well, in the front that might work. With a 17x9, 5.75" backspace, and a 255/45/17 you can probably thread the needle on clearance between the outer tie rod end and the fender. The problem is that the outer tie rod end clearance depends on the rim design. I know of a car that ran a 17x9" with a 6" backspace that just barely cleared the outer tie rod (using mustang Cobra R rims). But, I also know of several cars running Mustang Bullit rims that needed a spacer to get to 5.6" of backspace in order to clear the outer tie rod. With a 255/45/17, your tires would have the same fender clearance as mine with a 17x9 and as little as 5.6" of backspace. So, in theory you should be able to make it work. But that's assuming your car ends up with EXACTLY the same clearance I have, and that's not a great assumption.

In the back it depends on which B-body rear axle you have. If you have a 68-70 B-body 8 3/4" like I do, you'd have to trim the quarter lip back. That combination would only have .1" more clearance to the quarter as my combination of 295/35/18's on 18x10's with 7" of backspace. But since I cut over a 1/2" off the quarter lips on my car, it wouldn't clear unless you did the same. If you have a 65-67 B body 8 3/4, it will be really tight. That would put the combo .4" further in than mine, but again I cut the quarter lips back over a 1/2". It would be down to how wide that set of 255's really is, tire manufacturer would matter. Some might work, some might not. Maxing out the backspace at 5 7/8" would help a little, but it would still be close.

I ran the numbers for a 245 on a 17x8" with 5" of backspace too, just in case. In the front it would probably work, you'd have the same fender clearance as I do but your tie rod clearance wouldn't be an issue. In the back you'd be in exactly the same boat. With a 68-70 B body rear you'd have to cut the quarter lips back the same 1/2" I did. With a 65-67 B body rear you'd have .3", so, probably not enough to get away without at least doing a minor trim on the quarter lips.