What they said.
I store three cars every winter. Full tank of Shell ethanol free (most important), Stabil and methyl hydrade gas line anti freeze. Seems to work.
I don't know if m10 needs lead additive. I've not had valve problems, but I've read some cars do.
is the front cover getting cut too? current thinking is to reuse head bolts.
Per Toby, is block still in car? mileage on motor? You're getting into scope creep territory.
So,, to be clear, the car ran fine, you changed the harness, now it doesn't. So either you didn't have all those control boxes, and it's a new electrical problem, or, the new harness doesn't have the wiring mods that fed them?