An issue with these Cobra wheels, as well as most other 17" Mustang wheels, is going to be clearance to suspension parts. In tobysoldblue's photos, you can see how close these wheels with 5.72" BS get to the UBJ. This is really only a problem with the "tall" UBJ's. There are flat-top UBJ's that generate plenty of clearance, and you MAY be just fine if you remove the zerk fitting on the tall UBJ and use a plug instead. I swapped the flat top UBJ's in when I rebuilt my suspension to avoid the problem. Using the F/J/M-body spindle for BBP brakes will make this situation worse, as it's about 3/8" taller than the A-body BBP spindle.
Second is the clearance to the outer tie rod end. I think there are variations in the LBJ design from different manufacturers, because a friend of mine with a 68 Valiant and 73+ suspension has interference problems I don't have on my 69 Valiant with 73+ suspension. He has to use a thin space up front to clear the OTRE, where I've got about 1/8" between the OTRE and the wheel lip.
In the rear, I found that a 1" spacer on a stock A-body 8.25" rear was a great fit on my Valiant, using 245/45-17 tires. I then swapped in a 65-67 B-body 8.75" rear because it's the narrowest non-A-body rear you can find easily. It's about 1.25-1.5" wider than the A-body 8.25 rear, but the wheels still fit OK in back on my Valiant. I think it would be a better fit in a Demon/Duster/Cuda than a Valiant/Dart, since they have wider quarters, but it's still fine.
The tires are going to make a lot of difference, too. The 245/45 Kumho MX sticky tires on my Valiant have treads that are only 1/2" narrower than the 275/40 Goodyear Eagle F1-GS (Corvette) tires I tested. Be sure to check the tire specs on tirerack.com to see how wide the tires you want really are.
If the American Muscle wheels have a 73mm hub bore, just order some hub-centric rings for a 2000 Intrepid or a 2005 Charger and they'll fit perfectly on a BBP Mopar hub.
Clair