Just watch out for the pull out stock adjustment. No matter how you follow the G&P instructions, it's not going to ratchet for you. You have to make a similar modification as below to get that spring loaded stud to go in the index hole.

The best mod's that were made for the G&P pretty much all were achieved by Matt Noble. Matt had used his access to a 3D printer and printed parts e.g. a cut away mag base to allow for winding of the magazine for BB's, a mag holder to replace the stock one that also had the false release taps built-in, screen accurate sling, and a rounded back end for converting the G&P rectangular shape near the stock to a proper rounded shape ala. the screen used pulse rifle. Of course, you can not attach a sling to a G&P PR unless you had sling mounts. Best way to do that would be to get a metal barrel vent and a metal pull out stock with the sling loops soldered in already.