What places would it be good for temporarily attaching a pressure gage to check the oil pressure?

I know the 1st is the forward facing plug on the right side of the case.

I'm thinking that there is an identically sized plug in the head cover for the intake rocker shaft but I can't tell if that fed with oil.

This is what I am doing for a temporary look see.

I thickened the filter cover and tapped it 1/8" npt.

The aluminum piece is JB welded and has two screws tapped to ensure it does not come loose.

Goofy look when assembled.

It turns out the 60psi gauge is horrible at the low 2-4psi at idle and read zero.

Currently I have a 0-30 psi gauge with a valve I shut off then the engine is cold and the oil is thick.....I can open the valve once the oil is up to temp.

from what I understand, taking it from the front port will yield the same pressure.

I want to check the pressure at various points to check proper flow.

I don’t think the intake rocker shaft plug will work.  The shaft only has about .001” clearance.  I assume you aren’t considering removal of the head cover.  If you are not opposed to removing the head cover, it is easy to drill out one of the plugs (right or left) in the oil gallery, drill & tap 1/8 NPT, and install a fitting.  Most informative location would be left side of the head cover since it is adjacent to the most remote bearing.

You could also drill a small passage through the far left side of the left cam bearing into the void between the rocker shaft and the plug you are considering.  I do that to my head covers to provide some lubrication for the  intake rocker shaft since it floats ( unlike the Exh shaft which is fixed).  I still don’t think that is the ideal location for instrumentation since the oil flow is throttled by the cam bearing.  However it should give you a good idea how bad things can get pressure wise.  I suspect the pressure in that location should be bleak.

Dave’s filter cover mod is sweet.  Quick & dirty.  All you need is a spare filter cover.