I just sent a note to one of my customers in France who has a 416 stroker 340 he built there, maybe he knows of someone who can balance the motor for you.

I would probably call Diamod pistons as they seem to do a fair amount of Dished pistons with quench for strokers, I'm certain they can make a set of 8.5:1 blower pistons for you.

A balanced assembly could a good/more economical way to go as long as you have the block machined and know your deck height and bore size in advance