So I bought an 8.75" B body housing, axles and perches for $200...

I don't believe those early tapered axle drums will work on later flanged axles, although I could be wrong... wouldn't be the first time. :)

Yeah most (if not all) of the tapered axle brakes are the Lockheed style, not the later Bendix style so I don’t believe any of the brake parts interchange.

I believe the swap over to the Bendix style brakes corresponded to the changeover from the tapered axles but I’m not 100% on that, it looks like all the part numbers changeover at the same time.