RAPIER, I'm a little confused. Are you saying you can get 2500 f/s with a 150 gr. cast in a 7.62x39, without straining things? Are the barrels you are using somewhat longer than the 16.5" AK/AKM pattern barrels?
I looked up data for 150 gr. projectiles in the 7.62x39 using H322, and Hodgdon lists 28.5/H322/150 gr. Hdy. SP as giving 2192 f/s from a 24" test barrel. Granted, the projectile listed by Hodgdon was a j-word, while you will be using PC'd projectiles, but will the added lubricity of your PC'd rounds get you another 300 f/s from similar or shorter length barrel?
I checked data using AA #2200 and found that 29.0/AA#2200/150 gr. Sierra SPT gave them 2291 f/s from a 21" barrel, which is closer to your goal, but still 8% under in terms of velocity.
This isn't a criticism, so much as my expressing concern that you might be pushing the limits of the platform, as you try to obtain "miniature .308 performance" from it.
I had a Czech Vz-52 rifle in 7.62x45 with which I experimented, and found that I could improve on the AK round by ~125 f/s in the same bullet weights. I got nowhere near a .308 nor even a .30-40 Krag, before getting pressure signs.