Calling it a dog is a stretch and you can blow up a 904 pretty easy behind a 318 with a 2bbl , did it myself at 17yrs old .
But I agree I would just fix the 904 , one thing that one has to do to switch to a 727 in an A body with column shift is to fab up the shift linkage , column shift 727's were few and far between and finding originals is not easy and no one repops the stuff .