Jrt

Hi guys new here. I bought my son a 65 Barracuda /6, a three speed on the column. I want to to put a modified but streetable 318, and a 904 tranny in it, can someone tell me how involved this will be. Also can anyone tell me what size rear came in this vehicle from the factory, and do i need to change it for the 318 setup? Oh yea i'm looking for around 300hp, on the engine.