727 Torque converter in 904? If not, what should I get?

A 727 converter will not work in a 904. If you measure the diameter of the converter hub(the part that goes into the pump), you'll see that the 727 is a different size than the 904 hub. Make sure you tell Coan that you're using a 904 transmission and it will be going behind a 340. As Hellrats said, the stall on a 340 converter is about 2400 RPM, and with the minor modifications to the engine, and I think it should suit you just fine. The catch though is the unknown specifications on the cam. Unless there was a dyno sheet available, our performance converter/engine guru always wanted the cam specs were important to ensure the customer got the right converter.