Maybe instead of a big financial commitment to a new engine & trans, find some inexpensive used stuff, plug it in, and get back to the track. Kinda depends on whether the fun for you is in competing, or chasing an ET/MPH goal.
My own car has turned into more of an engineering/tuning hobby, and for the competition deal I want to build or buy a slower car that doesn't require as much work. For that matter, I've actually taken rental cars to the track and had a great time.