External or internal balance?

If given a choice I'd go with internal balance. The one stroker I built I bought the induvial pieces as a "kit" was available for the options I wanted. Had my machinist balance it for me. My dad bought a Scat 408 kit that was "balanced". After he got it running that thing shook worse than some of the stock stroke motors we had in the past that we bored .030 stuck pistons and rod bolts and slapped together. He ended up taking it apart and had my machinist balance it and now it's smooth as can be. My old machinist would just take weight of 1 piston and rod and then balances the crank for that. My new machinist makes all the pistons, rods weigh the same and then balances the crank and it makes a world of difference.