Lets talk push button transmissions

I'm in sunny SoCal. My 65 barracuda has floor shift automatic; does that mean l can only use a 65 trans?
65 went to cable shift

That depends. All 727s in 65 were a one year only cable shift slip yoke. I believe, but could be wrong, that A body 904s in 65 were still ball and trunnion flange output. If you currently have a flange output 904 you should be able to use an earlier transmission provided it has the right valve body. Just re use your existing valve body if there is an issue.
there were some ball and trunion 65 cable shifted 727s as well, mostly early model years. I've got one sitting in the shop actually. But it's from a B body. That said, they were one year only as you said. The buggiest thing to watch for on the 65s, is while most went to floor shift, there were some that were still column shift, the cable lengths are different.