I've got a couple of these Chinese drums - bought back in the days when piles of them were sitting on gun show tables for $65. They're almost identical to the 7.62x39 drums with a taller "tower" welded on top.
Be prepared to dick with them a little bit. But on the ones I have, once I got all the diesel cleaned out, lubed 'em, and made a few minor adjustments where the rotor was dragging on the outside housing, they actually worked pretty good!
The only thing you may have problem with is if you're planning to use them full-auto. All of mine will only feed 3 rounds on full-auto then the bolt will close on an empty chamber. It looks like the drum just isn't fast enough to feed FA and after 3 rounds the new cartridge is too low and the bolt rides over the top. But on Semi you can fire 120 rnds. without a hitch as fast as you can pull the trigger.
So if you've got the money to burn and you already know what to expect from dealing with the 75 rnd. units, go ahead and have some fun!