What to do with this 350?

[Zenwren]

My 69 C10 has what appears to be it's original 350, the odometer shows (1)06k which I believe is original. I've only driven the truck a couple hundred miles but the engine seems fairly sound... EXCEPT about 30% of the time the cooling system doesn't hold pressure. It doesn't seem to get hot or lose massive amounts of coolant, but the last time it did it I noticed it was bubbling through the upper hose and into the coolant overflow bottle. The oil looks clean. I have tried a new radiator cap, and replacing the intake gasket. About the only thing I can think of now is head gaskets. Someone slapped some L98 aluminum heads on it about 20 years ago which doesn't fill me with confidence. So my options are as follows...

1. Have the L98's resurfaced and replace the gaskets and hope the rest of the engine is good.

2. Replace the heads with some halfway decent junkyard iron heads

3. Crate motor and be done with it

What I'm looking for is a simple reliable cruiser in this hot Arizona desert. Is there anything else I should check before pulling this pig out? Any other options I should consider?