What engine hoist for pulling engine/trans while on cribs?

Is it Safe for me to Pull the Engine out by the Intake Manifold on a '65 273 with the lil 5/16" Bolts?

Absolutely. Look up the tensile strength of a 5/16 bolt. As long as the threads are good in the manifold, you're fine.

I would think it would be OK. Make sure to use Grade 8 bolts.