Magnum Swap Transmission Options

hello all!
I am considering doing a magnum swap in my 65 Valiant from my slant six and am wondering what I should do for a transmission. I plan on converting to a carburetor set-up to keep things simple. I am not looking to race the car; I just want it to be fun to drive. I know that I can make a 904 or a 727 work but are there other options that might be better? I would like to keep it automatic. Thanks!