A bit pricey, but I got the Hayley Heavy Duty chest rig to run DSA58/FAL magazines. Works a treat and you can get Kydex inserts.
If you want to go retro, there are Alice pouches available for M14 mags, and an M16 Alice mag will take 2x 7.62 mags, but you might want to put foam boosters in the bottom to cope with the reduced length.