Such a painful bug, you add one extra mod and everything hashes differently w/ no problems, haha.
Anyways, I restored the setup to one that I could confirm crashes on startup with GT6 b412, and then just switched out to b413 and that got me to the main menu just fine (and a SP world to check out the NEI entries for the induction smelter).
I haven’t done more than light testing to see if it regressed anything, but it seems to work at a cursory glance.
Thank you 