Good deal! It looks like its the whole USGI conversion over. I bet the sights are USGI too. I have a poly tech IDE import too and the original sights are awful. The elevation shaft is undersized with crappy thread pitch, some of which have stripped off. The peep sight moves around like it's doing the jitter-bug and the wind age thread won't grab a USGI elevation shaft. The other thing left is the sight block and the retainer plate...whats the point! USGI sight conversion for me.
Anyway nice score! You still can get USGI stocks for $35 from the CMP and refinish them to awesome condition. You might be able to get that green paint of with some effort, you might have a nice Springfield stock.
Great score! Good luck with it! Like some one else said, the original base value of the Polytech was $400 and you have at least $600 in upgrade USGI parts not to mention Gunsmithing bill, gas money, many gun show money entry costs, and lots of your time. Good score!