Sounds like possibly a couple of problems here. First possible problem......I would never buy a brake drum from Mac's.
Secondly, you say '40-type brake drums and hubs. You also said something about bent hub. How did you separate the original drums from the hub? If you tried to press, or hammer the studs out of the hub, that is when it got bent. The factory studs are swedged once the drum is installed. This physically changes the shape of the steel stud to hold the stud in, and to lock the drum on. The only way to properly remove the five studs (and the drum) is to use a cutter to cut the swedge away from each stud. If you hammered or pressed them out, you've most-likely ruined your hubs. If it makes you feel ANY better at all, I learned this the hard way almost fifty years ago.
GOOD quality drums are out there. Cheap, junk drums are out there also. Type "MT Car Products" into your browser for GOOD drums and hubs and associated, requisite parts. Hope this helps! DD