First, thanks for the advice on the Howards lifters. Valve train is much quieter now and not popping out pushrods...and higher oil pressure is great too!! Those Comp Cam lifters were causing more that one problem for me, apparently.

I have the oil pump spring all shimmed up, so I know that's not it. If I ever get to the point where I feel I have too much pressure, I'll remove the shims and go from there. Right now, I am just eliminating that variable.

The adjuster screws are NOT drilled all the way thru. They are drilled part way thru and then cross drilled, which leads to an other drilling thru the rocker. So oil goes thru the rocker, into the screw, and then down into the cup (as you would expect.) No oil comes thru the top of the screw...only the bottom.
Of course, in my case, since I have oiling pushrods, the oil is going the 'wrong way' and into the rocker shaft and then adding to the total volume.

This time when I was priming it, I was not on TDC, so the oil was not coming into the shaft from the heads at that time. Oil was coming thru the push rods and then eventually out of the large hole on top rockers. But it was not very much oil. It was what I would consider a 'reasonable' amount.

Now when I have the engine lined up t TDC and the oil is coming thru both the pushrods AND thru the head, then there is so much oil that it shoots way up into the air thru that hole in the rocker.

In summary, I don't know which method is contributing the most oil (thru the head which is a lot, but metered; or thru the pushrods which seems like a reasonable amount, but continuous), but the combination of the two is obviously too much.
And I think that hole in the top of the rockers just lets to much oil out, too quickly.