Wheels

Yup, I agree. Parts are easier find for the BBP brakes, both front and rear. Currently I think most of the parts are available to rebuild the SBP drum brakes including the drums, not sure about the KH disks. There have definitely been stretches between production runs where you could not get new SBP drums though. But even if the parts are available the SBP parts are more expensive. The BBP rear drums have more surface area, so, more braking force. The KH disks and 73+ BBP single piston disks are about the same for stopping power unless you upgrade to the later 11.75" disks (which you can do with 15" rims!). BBP uses 1/2" studs instead of 7/16", so, the studs are are stronger, and the upper ball joints are larger on the BBP spindles. Although I don't think I've ever heard of anyone breaking one of the small upper ball joints. Wheel bearings are larger for the BBP spindles and disks as well, so they should be stronger/last longer for the BBP set up as well. Again, probably not a big deal for most people.

Wheels are available for the 5x4" pattern, but your selection is pretty much limited to stock styles and maybe a couple different aftermarket styles (ie, cragars) unless you go custom. With the BBP the sky's the limit, you can get pretty much any style wheel you'd like. And more backspacing options, so more tire size options too. Most of the wheels offered for SBP only have a couple of width and backspace options, so tire choice it limited further.

Honestly I wouldn't mess with reconditioning a set of SBP brakes if I was going to buy a new set of rims. By the time you've reconditioned and bought new parts for the SBP set up you're not going to be too far off the price of converting to BBP, and if you do that life will be a lot easier when it comes to replacing parts in the future, not to mention choosing wheels and tires.