Hi Patrick-

I should probably let seewin or one of the other M54 experts answer your question, b/c short of trying it myself I can’t be sure of the answer.

I think that the barrel and receiver from a standard M54 would drop into a pre-war M70 stock without difficulty, except maybe for the clearing the trigger mechanism which is different between the two models.  There would be two things, however, that would not necessarily work.  First is that the M54 bolt (if unaltered) did not require the stock to be relieved for the bolt handle (except for a slight dished out curve).  Of course if your Grad Dad’s gun has been altered for scope use, you’d need that cut out and the M70 stock would be fine.

Second is that the one-piece bottom metal of the M54 and the floor plate/trigger guard assembly of the M70 are quite different:

So there might be some inletting required to make that fit.  It could probably be made to work, but might not be pretty.  I’ll wait for a better informed answer, though…

Depending on whether your rifle is a “1st standard rifle” or “NRA standard rifle”, whether it has been altered for scope mounting or not, and whether you consider a recoil pad sacrilege, I might ask around, e.g. put a WTB post on this site, and see if any WACA members has a spare M54 take-off stock that would work for you.  Unfortunately, I do not, as I only own two M54s and they are both intact.  If you are looking for an intact unaltered original stock it might take a while.  But one that’s relieved for a modified bolt handle +/- recoil pad might be easy to find?  

Best,

Lou