I think JPP would be a great fit as a 3-4 DE. From what I understand, they're more run-stuffers anyway, and at the end of the day that's really JPP's strength. We'll just have to wait for the games to stop meaning something so that he can make some plays from that spot. We'll probably need another big, beefy DE on the other side of the line, and I bet Snacks and Tomlinson rotate as the nose tackle (which is good to keep them both fresh).
Vernon IMHO would be a perfect fit as a strongside backer in the 3-4. I could see him being an absolute beast there if he stays healthy.
But most importantly, switching from a 4-3 really means we're not going to ignore the entire linebacking unit like we did for ten years under Reese, which has me VERY excited.