Along with what Pikko said -
Obitsus and BJDs can hybridize, I'm just not sure how it's done? I've seen - I believe - a Doll-Zone Megi girl on a 50cm Obitsu body, but I can't find any of her photos right now. So, in theory, yes? You'd have to do something about the neck mechanism and it should be fine.
That being said I am 100% that those heads are
recasts (bootleg/illegal copies) and are
not something you should be buying. Not only does the quality of those particular recasts look horrible, but owning a recast in this hobby is a death-sentence and incredibly harmful on the doll companies and community as a whole. If you are looking for a cheap BJD head to practice with, might I suggest the
Doll-Family H practice heads? (Link is to MintonCard, an authorized dealer for Doll-Family and many other companies.) My neighbor has one of the MSD heads and he's pretty cute~
You might also consider looking into Luts Event Heads, as those can be very cheap to buy secondhand and very cute! (I love all four of mine.) Many companies offer affordable heads, and you can always browse the second-hand market to find even better deals.