Keep in mind that if you do as Murray has suggested on doing the pump/spline upgrade, the converter will have to be custom built for you. The pilot(fits into the hole in the crankshaft) on the early 904's measures 1.550"(to 1967) and the pilot size on the 1968 and up measures 1.810.
I would choose to upgrade so that I can use the later model converter’s. I wanted to switch up the converter when I initially put the 340 in but it was a real pain to try to find something that would work.
