ask around if there is a local gunsmith who has a laser engraver, most well equipped 07s will have a laser engraver and just have him engraved PISTOL on your stripped lower. it shouldn't cost that much to do that kind of simple work. especially since it isn't a complicated design
anyway, that is a option, instead of hunting around for a AR15 lower with PISTOL already engraved
the local gunsmith I know has what looks like a copy machine, he does a lot of work engraving pictures/logo/writing on the blank side of AR mag well, from a library of pictures etc... on his computer
THE best option is to do what 99.9 percent of the folks do, just buy a stripped lower and just "build" that as a pistol with no PISTOL engraving on it. since it is not a requirement to do that. save the bucks you would have thrown away on that toward something better, like putting that money toward a upper, ammo etc....