DSE (Detroit Speed & Engineering) makes an updated subframe with R&P steering for the '70-'81 f-bods, but it's fairly costly. Don't know if it's set up to take a Pontiac engine, but that should be a simple change. It does, however, also get you a 'Vette front suspension set up.
I seem to recall seeing something about a 2nd gen f-bod R&P conversion in a "new parts" section of a magazine recently, but don't exactly recall either the mag or vendor. (I'm having a senior moment) The most recent mags I've looked at are the newest issues of Car Craft and High Performance Chevy. As I said, I don't quite recall the supplier, however Steeroids or Flaming River Industries are sticking in my mind for some reason...
Good luck with your T/A. I had a '77 T/A for MANY years...fun cars!