The Yugoslavian 8 mm M76 bolt is a perfect fit. Get one in good condition that doesn't have an eroded firing pin hole. Maybe an M76 bolt carrier too but that may not be needed. The ejector tip will need to be extended in the receiver. The Soviet RPK manual calls for a weld filler that cools to a minimum hardness of Rockwell 40 C in repairing the ejector with welding. The plastic 308 PSL magazines are not very good quality. 308 Galil magazines can be made to fit the 308 PSL but I don't know what mods would be required of the 7.62x54R receiver for 308 magazines.