Transmission advice

Hi All,
My 68 Barracuda is getting a new engine and rear end... a newly rebuilt 360 that should be good for 350 hp. Currently has straight 6 and /6 904.

I'm going to switch out the rear end to an 8.75" w/ 3.55 suregrip and also transmission (obviously). Here are my transmission choices:

1) A 727 that was rebuilt like 12 years ago, put in a Dart project, and left to rot. I bought the Dart for parts and grabbed this transmission (Dart had a 360). I drove this car roughly one block up a hill in Low to get into the garage where I stripped it down, sold the shell, and know nothing more about it.
2) A 904 from a running, driving 1978 Plymouth Volare. Based on the date I believe this to be one of the first lockup 904s.

Thoughts? This car will not be on the racetrack.

Thanks!