I remember T/A style heads had a 0.550" offset rocker arm, a lot of work these days for little return. Unless you were racing a class that specified a factory head had to be run, not a lot of point to doing it really.
I have a truck headed 360, I did toy with the idea of doing it with those and making my own offset arms. But only because I like making that kind of stuff and can do it all myself. Expensive exercise if someone is doing it for me.