Bill, allot of people mistakenly install the input shaft in backwards seen that booboo many times. Sometime it takes the pump out and sometimes they will run for years that way depending on the power you are throwing at it I guess? I was surprised that coan tranny didnt have any better components in it than that but then again a stock 400 is pretty stout to begin with. I had a 73 nova w/ t 400 that I ran for 8 years with the input shaft in backwards, never knew it till I took it apart to freshen it up.
I personally think a higher stall converter would work better but then again dont know if your driving this car on the street or if its a pure racer, I like the 8 inch 5500's myself. I changed a 10 inch 3500 stall on one of my old drag cars and went to a 8 inch 5500 and it picked up the car almost 3 tenths. Goodluck, Charles