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Take the extra oil, cheapest 20W50 you can find, keep your foot out of it, and as long as it is ticking it will run. Just rebuilt a 302 with about 170,000 on it. It was still runnning but my son heard a louder knock from the bottom end and he had the money so we rebuilt it. Pulled the heads and #8, #6, #2 & #3 pistons all had broken rings, (3 or more pieces), #8 & #3 piston had holes burn through the tops that you could stick a pencil through, AND IT WAS STILL RUNNING and he was driving it everyday. I'd like to see a Chevy do that!!
I too would vote first to look for a cracked exhaust manifold.
Leaking exhaust manifold may cook the vac lines over the passenger side.
If you need an emergency fix, reflective foil duct tape can shield vulnerable components.
The 86 engine I just pulled from my truck had over 300,000 miles on it and it would burn about a quart of oil a day and had some knarly piston slap, but I could still rev the hell out of it! I tried to blow it up but it wouldnt go! Dont use 20w50, get some 30HD. You should be fine on that engine, its bulletproof.