it can be done likely on a psl how ever you will still need to lengthen the mag well as well as also deal with a much larger bolt face. It all depends on what x54 ammo your looking at some is really hot. If you can get a reciver and trunion cheap go for it you will still need a carrer and bolt. it may be possable to mod a standard bolt and trunion to work. Im not really sure if there are any real streangth gains over say a m70.
IMOO a ak 74 bolt on a Yugo trunuion should give the most streangth possable with standard AK parts. that are not super hard to find. Im thinking a AK 74 trunion would possably in second place.
If I had no parts lying here Id buy a bulgy ALK 74 kit as a doner kit and go from there. I have yet to see any documented cases of a trunion failure in any calibur or conversion. it seems the bolt would be the weak link. untill some one actualy has a failure its hard to say.
My 243 build is back on the bench and I hope to unt with it next month. after that I plan on some hot load testing and care full measure ments of head space changes.