Jon, first thing welcome to the Afourian Forum!
Lots os stuff listed to dig through. Did you check for spark when the engine stalled? Your ignition upgrade may not include the properly rated coil and it is "opening" once it gets hot and then "closes" after cooling to fire up again. There has been much todo regarding this on the forum.
As far as the coolant leaking do you see any in the bilge or leaking anywhere on the engine? If not and you are using that much coolant it's probably time to check the intake/exhaust manifolds integrity. Not to bad of a job.
Don't R&R the head unless it is needed and it is not YET! A simple compression check will let us know if you are loosing coolant throuugh the heads gasket. Have you done a compression check?
Remember to close the water intake while cranking in hard starting diagnosis so you don't fill the exhaust risking water encroachment from the exhaust side to the engine
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Dave Neptune