Replacing
I will most likely replace to motor with a new 6 long block, the old (per-60's) Chevy down here like to over heat and oil failure was big the killer too. Unleaded gas brings new issues, this 6 has had oil problems all its life rebulit twice, and 11 oil pumps later tells me there must be a design flaw!
I will rebuild the old motor ( I will teach my step-son when he is ready). But I what to get it out on the road this spring, so a new chevy long block striaght 6 that can run unleaded and I have nuff hp to put in and A/C unit (there is nuff room to hide and evaporator and fan housing unit behind the dash).