that is why the forum is here. There are authors of books on this forum and folks with 30-50 years experience, plus many eyes to catch possible "bad" things.
As the saying goes, buy books before guns. Study, ask questions, etc. I doubt you'd buy an "ole" speedboat before checking her out ahead of time, same with lugers
I personally think it would be better to start with a mostly there carbine or the like, and have it restored. A frame is fine, but all those correct parts to gather...
I did wonder at the Ad on Adam's website; "fresh from Mexico..." Its a frame. A frame is the part that is controlled by the gov't... So actually if true, I "believe" it should have gone through the import process and I believe be import marked.
Ed