Theoretical question: converting AR-15 mags to mini-14?

Hey guys...long time lurker, first time poster. I'm waiting to see if I won my online auction for a Mini-14 RR, and was pondering the magazine question. A few threads back, someone mentioned a 'do-it-all' magazine that worked in both the AR-15 and mini-14. As would be expected, this after-market magazine was a pile-of-you-know-what, but it got me thinking - how hard would it be to convert AR-15 mags to fit the mini-14 magwell? Would it be something simple like grinding down the side-latch on the AR-15 mag and adding a plate on the back so the mini could latch on to it?

Anybody ever try this? Like the title says, it's just a theoretical question - I'm okay with buying a few PMI/Thermolds and calling it good, but how hard would it really be to modify the AR-15 mag to function in a mini-14?