Lots of info there that I hadn't seen before. Note all the expensive special tools required to fool around with that balance shaft. Then, if you modify the engine by changing to better pistons, rods and crankshaft, one has to wonder what has to be done to that shaft. Glad that I don't have to fool around with that engine. I'd rather go small block chevy at that point. Glad that I'm not a service mechanic these days trying to make a living.
You could use short Chevy pistons and an even longer rod. There probably aren't any cranks available. If you left the balance shaft out it wouldn't be any worst then what we have now. I know they were mostly set-up for front wheel drive but I have seen these engines in late 90s Camaros in salvage yards so they must have provisions for RWD. They went to the 2.8/3.1 bell housing so the flywheel/flexplate must be smaller (maybe that's the reason for the balance shaft).
The series II is an awesome motor. They are 4 bolt mains for at least the supercharged blocks. ive heard that allot of the stage motor development went into the series II blocks. Equal distance on all the intake and exaust ports etc. they are very strong and can actually be pushed harder than our 109 blocks.