the #GrinMAC itself is supposed to be 8.4lb, but with the heavier spokes+rim and tire+tube (still 1.75in but going from kenda kontact to conti tour and a slime heavy-duty tube) The old hub+spokes+rim+tire+tube was 3.3lb, new stuff 12.7 (no cassette on either weight.)

chainstays need to get 8mm more between them, 130 original. Can I put a threaded rod between them and run two nuts outward? ...

we've arrived at 138, but that was hard work so now we're tired (but we're also "it would fit now, we could keep going") 🥱

Interference between the rack afixment screw protrusion and the torque arm being a much larger flat surface than many bikes might assume to fit there. Otherwise looking fine.

The chainstay steps down right where the torque arm mount needs to be, and I have smaller hose clamps with the same band. Do you cut those off or tuck the tail into shrink wrap or something?

Do I bend the torque arm? (No. ICYMI, Cold-bending aluminum is bad for fatigue life.)