I honestly haven't a clue on retro-fitting it to something else. I know a 7.62 mag is a good bit larger then the magwell of the Norinco .223's, never messed with a SAR3 or the Weiger mags. Since a 5.45 mag fits both the Norinco and Rom. .223's I'd guess it might take some serious ingeniuty, but like I said, I really don't know.
Tell ya what though, if I had a Poly .223 I'd want one. The Norinco 40's are scarce enough as it is, a drum would be awesome!