Sorry to resurrect an old thread, but I have an M88 and it's a great gun, I like it so much I plan to buy another one!
I altered my M88 to take standard Tokarev mags, it's a pain, but I did it.....you have to tap out the 2 pins that hold the mag well block in, which is a task in itself. I managed to get them out but put a few "pings" in my grip frame and on the backstrap from the punch slipping
It's OK, the Hogue Handall covers them up
Now for the fun part......Zastava added an extra "ledge" on the hammer group to support the 9mm magazine.......to make the Tok mags work you have to file away this ledge, in other words, make it look the same as a Tokarev hammer group, so the mag can slide up flush against it. It took me a week, working an hour or so a day, to file this ledge off. I didn't want to risk using a Dremel tool and mar the feed lips, so I did it all by hand..........hope you have a good radio station on or something, because this gets boring
BUT it can be done..........like the OP, I bought this as a fun gun/range beater/trainer etc. so I wanted to make use of the 10+ Tok mags I already have, rather than paying $17 each for M88 mags. My gun only came with one mag, so I figured I can alter the gun for free, or pay for more mags. I like to have lots of mags for guns I use as range shooters, so I can stick them in my pocket and just reload. Getting 10 or more M88 mags would put me in more than I paid for the gun. Since I already have a Tokarev, I like having mag commonality.