Slant 6 hot running issues
It is very much worth your while to get the
good gaskets for the manifolds-to-head and intake-to-exhaust junctions. Install tech tips
here. And if your exhaust manifold fails inspection (cracked, warped, gasket surfaces no longer flat, etc), see
here.
And while you are at it, consider ditching the rinky-dink, cold-blooded factory choke setup for a № 1232
Electric choke kits, which—unlike the original, is adjustable (hallelujah, praise be!).