My New Wheel/Tire Combo

Hi people, just new to using the forum. I have a few questions about wheels and tires. I have a 68 fastback and want as much wheel and tire I can get on there. I m about to put the larger bolt pattern axles on the 8.75 rear and was considering the Brewer's axles that don't require any brake changes except re-drilling the drums. For test purposes I drilled out a small bolt pattern on a 15x8 black rim that has an old G50/15 T/A on it. The rim has a 4 3/8 back spacing. So, it seems to me that it gives me just about 3/4 of an inch of space to the leaf spring and doesn't stick out the other way.
My question is regarding some of the combos that guys are talking about; are they using stock width axles and brakes or are they using large bolt pattern with the bigger brakes?