Are you sure (with full respect !) ?
I was said precisely that Essex V6 (Capri) were internally balanced, that means the flywheel was factory made as neutral balanced...
See here : http://www.hinesindustries.com/documents/reciprocalmass.pdf
Après tout, I'm gonna rebalance it, just to be sure to sleep well...
The Essex V6 is external, whether you "respect" the information or not that is a fact. That big lump of cast iron on one side sort of gives the game away.
You do not need to touch the damper that will be OK.
We do balancing and we do American V8s, if you do need help let me know.
Mike