Low oil pressure?!

[Russ72C10]

Lately I've noticed the oil pressure in my '72 is not stable. It still has a factory gauge in it (reads 80psi according to the print on the gauge)... and at idle it'll sit near 10psi. Under easy acceleration (normal driving) it'll rise to 20psi or so.... maybe 25, but never goes higher than that. IF I floor it, the oil pressure sinks to nearly nothing. I haven't noticed this until recently.

Also, there is some blowby that comes out of the hole where the valve cover breather goes. And with a few good revs, there's a slight amount of bluish smoke that comes out of the exhaust.

Do all of those symptoms sound like they could be caused by the failure (or wear) of the same part? And if so, what does it sound like the problem is?

I'm thinking some heavier weight oil may do the trick until I get the engine rebuilt this winter.....

I'd appreciate any info or tips...

Thanks!!