Not sure if anyone really recommended it directly or indirectly, but please don't buy a spare bolt just to preserve yours unless you're prepared to do all the work necessary to assure it fits properly. Unlike an MP40, the bolt in a MP44 has to be headspaced and trying to preserve the parts in your rifle could actually do harm unless done right. Just putting that out there because I don't want you to get hurt or damage your new prize. The StG marked rifles are very interesting and few and far between.

Does the stock have ribs on the back, and is it all one thickness including the section where it goes into the sheet metal attachment?