Not arguing but in 40 odd Guzzi years I've never seen this happen, would still scare me now.
Only ref I have is 10psi for every 1K engine revs, I've only ever bumped it for higher revs.
I'd have to fit gauge to see what was going on, just peace of mind, sounds like something well worn to me, oil light doesn't come on till well stopped in my exp.
If yours flickers, maybe is acceptable,
But on rebuilt engine ?
As I said its an issue with the engine or oil system and on a rebuilt unit I would prefer to know why but I wouldn't be losing sleep over it. A friend had a LM4 with around 20000klms on it years ago that did the same thing when he switched to Mobil 1 10w-30.
When he did the next oil change he went back to 20w-50 and it didn't happen anymore. Ran fine though and no issues before or after.
Some engines just have an accumulation of tolerances I think that shows up at idle. People get too wound up about oil pressure. As long as you have something reasonable you will be fine.
Was watching a youtube clip on a Racing Cobra Daytona (in car) lapping recently with full data logging on screen. Powered by a big V8 of some description, probably a Ford side oiler 427 spinning to near 7000rpm. I dont think the oil pressure got over about 48psi at any time. No surge or high temps either.
So 10psi/1000 is a yardstick only, many engines survive happily on less. Its really about flow not pressure, a common mistake is to assume more pressure is better, not actually so. When you have adequate any additional is just wasted power.
Its not the pump pressure keeping the bearing journals apart, that's done by hydrodynamic lubrication. The pump pressure is just to keep the supply of oil up to the bearings and as I said when you have adequate then thats all you need.
Ciao
