'95 3.0 L Mercruiser - Oil pressure problems and valve noises

[86angler]

High I am new to this forum, but I was looking for some advice. I have a '95 3.0L LX mercruiser. I bought the boat really cheap, and was told the engine was beyond repair. I tore the engine down and rebuilt on the cheap (yes I know that is not a good idea) I have done all of the following:
Machined head - reset valves
2 new valves - as they were too worn to reseat.
New crank and piston rod end bearings
new gaskets where needed.
new lifters
Standard maintenance items (Plugs, wires, belts hoses etc.)
And pretty much just checked everthing else and put it back together.

The engine runs pretty good, but I am still hearing valve clatter. My oil pressure stays around 25 psi and goes up to 40 when at W.O.T.

I have adjusted the valves several times - both with the engine off and with the engine running (what a mess!) all per the mecriuser service manual. I have also exhautively checked the timing per the "special procedures" required for the electronic ignition, I think that is pretty good. I plan to check the valaves again after running for about 10 hours - the last trip I run it for about 5 hours - so I was thinking I would go out one more time before readjusting the valves. I was pretty methodical about the valves - so I also think I got that right - but I am hoping it helps to check them one more time soon.

So There is the valve clatter and also the last time I was out when running just below W.O.T (about 3500 RPM) the oil pressure suddenly went to zero - of course I shut the engine down ASAP. When I got the nerve I started it back up - and the oil pressure went back to normal. This got me thinking about the oil pump, could the valves be getting enough lubricant?

I am thinking there could be three possible probelms
1) Bad electrical connection on the sending switch - I doubt I am that lucky - and that does not explain the valve clatter that just will not go away.

2) dirt in the oil - I was careful during the engine teardown to keep everything clean, but I am thinking there my be a clog in a lifter or other oil passage that caused the oil pressure to drop. I could change the oil and filter and hope the filter caught the dirt. Then maybe the lifter that was stcuk is now freed-up and the valave adjustment will solve all my problems.

3) My oil pump is about to go bad or my pick-up id clogged - yes I should have bought a new one by now, but I am on a tight budget, I guess I am optimistic.

In summary - Summer is just starting, and after 14 months of engine work, fiberglass, and electrical work on the weekends. I am finally getting some use out of the boat. Does anyone have any suggestions on cleaning/checking the oil pump without having to remove the engine yet again? I would like to just blame it on some dirt in the oil, and hope that after a few running hours the engine will break-in, allow me to properly adjust the valves and I will be good to go - is this just wishful thinking?

How much risk am I taking by putting off the oil pump replacement until after a few good fishing trips... at lower RPMS maybe to test the dirty oil theory?

Thanks in advance - you may all just respond that only an idiot would not replace the oil pump after all this work - maybe writing this has just allowed me to convince myself to just bite the bullet and get it done....

[Bond-o]

Ayuh,... Welcome Aboard,...
I'd start with Checkin' the gauge....
mount a mechanical gauge to the motor...

Then change the oil, 'n filter...
You can check the drained oil, 'n filter for crud,...

Then Run it to see what happens...