Thank you, all.
The compression is standard VMC. 9.5:1, confirmed with Pat Downs (not 8.2 as VMC lists). The new pistons moved it up a touch, but assume it’s below 10:1.
I think I will try the welding cable. Seems like a cheap thing to try. Is there any improvement to ground?
VMC puts their cooler tucked up on the rear seat wall. It is thermostatic. Can someone post photos of where it should be closer to the wheel well?