:) I'm looking for some experiene when it comes to moving from a badly internal balanced 408 stroker to a corrected good balance external balanced engine with just added wights to the balanser and the flywheel. /Morten - Norway
You can't do what you're asking. If the rotating assembly is out of balance, just adding weight on the front and rear by using an external balance damper and tq converter won't work.
You have some residual unbalance, obviously enough that you're feeling it in the car. The issue is you don't know how much, or the exact angle, of that unbalance. When you put the external balance parts on, you're adding weight of a specific amount, and at a specific angle, which aren't necessarily where you need the extra weight.
Engine needs to come out, crank needs to go back, and be rebalanced with the external damper/converter.