[Roadsters] Dropping Oil Pressure at idle

[Hoon Kim]

Just when things are starting to come together, something else shows up.
Such is the nature of our cars.

After successfully (I hope), swapping out for a new larger alternator, I've
noticed that my oil pressure is now dropping when I'm at idle. This is
happening after the engine is warm. When I rev the engine or when I'm
travelling, the pressure returns to normal. I'm pretty sure it is not my oil
gauge since I let it drop until the engine stalled on me. I didn't notice
any knocking, just as the oil pressure drops, the engine gets rougher. I did
also recently replace the oil filter, but haven't changed the oil. Any ideas
on what it could be?

Is my engine wearing down (I hope not)?
Do I need a new oil pressure sending unit?
Do I need a new oil pump?
Do I need to add more oil or a heavier weight (don't think so)?

Thanks all.

Hoon
Early '67 1600