Before you run the engine any more, I'd suggest draining the oil and removing the filter. Strain the oil through a piece of T shirt material or something similar, and cut the filter open. Look for any sort of metallic debris. That squeal and oil pressure loss sounds suspiciously like a failing rod or main bearing, and if you continue to run the engine, it's likely you'll trash the crankshaft.

Older 283's from the late 1950's had a nasty habit of getting cracked piston skirts, but those just made a light knocking noise- - -no appreciable power or oil pressure loss.
Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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