Yep. Good approach if the rings are good.

I haven't used an old style smallblock gasket in 10 years. I'd start with Felpro but maybe that's not the best choice?

Interesting question. l think I'd loosen all intake valve rockers and pressurize crankcase to 1-2 psi with air. See if air is exiting throttle body. Test works better if you have a smoke machine...