I've never heard this engine run...as I said I bought it as a project car and was told the power train came from a 73 duster but never heard it run as it was half apart when I got it...Did 73 340 ever come with a 904? ...this is making me want to just put in a 727 as I can at least get parts that are supposed to work.😒
Whether a 340 came with a 904 is irrelevant to the balance issue. 340's came with a 727 in OEM configuration. The converter was the piece used to balance that end of an external 340. Putting a 727 behind it is not going to solve the balance issue, it's a converter weighting deal (if needed). Trans 904 or 727, in this case, is irrelevant
Can you get it started on a test stand with neutral balance pieces, check for vibration and go from there. Problem is you have no idea how the engine was balanced. It has a neutral balancer on it when you got it. May have been pulled because it vibrated, no way to know without the balance information/card.
