From pics, stock buick V6 rods with very clean looking SPS bolts which makes me think they were replaced, ARP main studs with stock main caps, and aftermarket pistons (most likely cast or hypers). Hope that helps
David, when Patrick (aka RUQWKNF) asked about the rules for XTSM before BG this year I posted that he probably was going to have to head over to Facebook as I am pretty sure all the discussions are done on that platform now days instead of here. You might want to get the ball rolling on there.
The first pic is of a Lightweight version of a JW internel balance flexplate. JW makes a standard version of that flexplate and external balance flexplate. Also out there are the overseas versions (Cat etc).