Don't worry too much for AK trunions handling the pressure - remember all those discussions about the .308 bolt vs. the 7.62x39 bolt, with comparison pics. If you use a bulged trunion Yugo kit as the start, it will have the same amount of metal as the 7.62x39 build. My Romy "G" kit build into .308 shows no signs of excessive wear.
Whatever you do, I'd recommend a .064" thick blank. Those .050" blanks may work as well, but you really want the extra metal to stiffen it up.