The M76 has a milled receiver, so the trunnion must be Romanian (or at least not from the M76). I don't know the diameter of an M76 barrel at the chamber, but it could be fitted to the PSL front trunnion an pinned in place. The bolt carrier should be a drop-in fit to the PSL receiver. You'd probably need to widen the PSL magazine well, but that's not so difficult.
The stock is a big part of what I like about the M76, though, so it seems like a counterproductive project to me. Particularly counterproductive when the end product is more expensive than a standard M76.