I am also setting up a rig for AK and 1911. First thing to warn you, many pouches WILL NOT work with an AK mag.
I have a Hellcat MK2, the body of which is very similiar to the rig you are looking at. You can fit AK mags in it, although with the way the top of the mag angles I suspect the bungee might not work. But The mags will be pretty darn secure. For $40 that chest rig is probably worth a try, as it is cheaper than most the inidivdual mag pouches for the AK.
As for Molle AK mag pouches, Blackhawk, HSGI, and Patriot Performance Materials all make them. CTD says that their 6-AR mag pouch will hold 4x AK mags, but I have tried one out and with 2 mags in each pouch you have maybe 1/4" of velcro engagement on the flap. The mags are REALLY, REALLY tight in the pouch too, but maybe it would loosen up a little over time. Being that the "first line" manufacturere pouches are $25 for a dual AK mag pouch and the CTD pouch is around $12 for a quad AK mag pouch, it might be worth buying one to try.