Wilwood drum spindle disc

The 73+ brakes are plenty for a street/strip set up. I run the stock 73+ calipers on the later 11.75" B/R body rotors and they work great. The lower ball joint is also a weak spot with the 9" drum spindles.

As far as the track width goes, if you're already switching from SBP to BBP you're buying new wheels anyway, and it's easy enough to get rims with a little more backspacing to account for the wider 73+ track width. It's only like 5/16" anyway. I ran 225/60/15's on my Duster with stock 15x7 cop rims, which have a 4.25" backspace. If you stay with 15" rims you can't go much bigger than that in the front anyway because there aren't any tires wider than that in a profile that will give you a suitable tire height in the front. A 235/60/15 is pretty much the top end of what you can do with a 15" rim in the front, 245/60/15's are too tall and good luck finding a 245 in a shorter profile. And of course if you're going to 17 or 18" rims the additional track width is actually a bonus as most 17/18" rims have more backspacing to begin with.

You also might want to check on the Wilwood calipers. I think most of their kits have piston dust seals on them now, but the older wilwood calipers didn't have any kind of dust seal on them. Not a problem for a track car, but for a regular street car it probably isn't the greatest idea.