I'm gonna pull the engine......then what?

[saxart]

So, the engine (350 SBC) in my '70 has a leaky oil-pan gasket and leaky rear main seal. It also must have bad valve guide seals because it puffs smoke on start up. I believe it had a valve cover gasket leak before I bought it as the lower end of the engine and the top of the trans is coated in that thick, dry, old sludge you get when something "used to leak". They do not leak anymore however, so I think the PO replaced those gaskets.

Anyway....Long story short, I'm pulling the engine and tranny (4-speed, manual) out of the truck this winter so that I can replace the aforementioned gaskets as well as clean up the engine bay in the process.

Here's where your opinions come in... Should I pull the heads and replace the head gaskets while I have this engine out? I'm not seeing any signs of head-gasket deterioration, but I believe this engine is a 1974 vintage, and doesn't appear to have had any rebuild work done to it, so in other words, they're old. (If it has been rebuilt, it's been quite awhile ago.) Because of this, I'm thinking the head gaskets should be replaced "just because" as I'm guessing they don't last forever.

Any thoughts or opinions are appreciated...