Engine/drivetrain vibration?

Another update on my situation with the rebuilt 340:

- It appears that the torque converter installed during my tranny rebuild (prior to the engine rebuild) did have the correct balancing weights, and was likely correct for the externally balanced '73 340. Unfortunately, those weights have now been removed from the TC in an attempt to correct the engine vibration (it didn't work).

- There may be some question as to whether the harmonic balancer that's been on the engine for years is the correct one. This is still TBD

- After talking with everyone involved in the engine rebuild, it appears the machine shop did NOT include the TC for the cast crank engine when they balanced the motor. Thus, it appears the balancing might have been done to the specs of an earlier (internally balanced) 340 -- not a externally balanced '73 motor

- Short of pulling the engine, sending it back to the machine shop and rebalancing everything with the correct TC included, my repair guy thinks it may be possible to have his tranny shop "spin" the current converter, compare that reading with the balancing done on the engine as part of the rebuild, and then add weights to the converter to compensate for the difference (i.e., the out of balance condition).

Obviously, you'd have to have same balancing configuration if you ever replaced the converter in the future.

Does this scenario sound do-able? If so, what should I be on the look-out for, and what should I be wary of?

This approach, if it works, would certainly be less painful than pulling the engine and starting all over again.

Thanks for all your help.