[Eplatvoet]

Alright; changing the timing - no luck. Taking side pipes off - no luck (but an impressive noise). In fact, the vibration sometimes now also shows up at idle rpm, just around 900-1000.
So we have run out of ideas. I don't want this engine to blow up on me so something needs to be done. Rather than trying the 3 different flywheel weights and rebalance the entire deal again we plan on either putting in a new Eagle stroker kit with a new flywheel or perhaps even a new engine and upgrade to a 427.
Thanks to everyone for the help.