Ok thanks guys I talked to the salesman and he said it was an externally balanced rotating assembly? The 340 is a 69 block according to the casting.stock other than a slight cam. I bought the car a few years back dont know too much about the engine other than that
External balance 340s were limited to late '72 and '73 model year engines, if your '69 340 is a stock bottom end, it will be internally balanced.
Therefore, you should be able to bolt your torque convertor up with a B&M 10239 flexplate, which is made for the LA360 balance with a904 convertor. But as @Johnny Mac (who IS the Blueprint rep, btw) said, you would probably be better off with a better, tailored to your needs convertor with the new motor.
