Extremely low oil pressure! HELP

Just to add salt to the wound, I bought my '78 and '79 Trans Am's from the same guy at the same time for $1,700. He had no idea what they would eventually be worth. They sat in my driveway covered up for years while I was building my house. And on a weird note, I went to the dudes house to pick them up early September 11, 2001.
The Bandit ran ok so my dad drove it home following me. I was driving the '78 which would barely get above 25 miles per hour - thrown rods, transmission gone.

Suddenly, the radio DJ's broke in with the news that an airplane had crashed into New York. All the traffic started speeding up to get to a TV somewhere. I could not make that thing go any faster for nothing.

It sure as hell goes faster now.  

That's awesome.  When I am all grown up and have a place of my own (a garage with an attic living area) I definitely want a late 70s ***  Not to mention a C3 Corvette, '69 GTO (which I have), '69 Skylark, and '68 442.  And my '86 Flareside F150 302.  Love 'em!

Back to the oil pressure issue.  Since I replaced that gasket and reinstalled the 160* t stat instead of the 180*, it idles with 20 psi and cruises @ 2,000 rpm with 40 psi.  Is that acceptable?  I'll still replace the oil filter with a K&N or something and change the oil again...  
1969 GTO, YS code 400, 350hp/445 ft lbs of torque (stock specs), LT headers, H-pipe, 750 Holley 4160, Ignitor II ignition.  Complete Painless wiring.

What is the rpm at idle.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

20 warm @ idle  
1969 GTO, YS code 400, 350hp/445 ft lbs of torque (stock specs), LT headers, H-pipe, 750 Holley 4160, Ignitor II ignition.  Complete Painless wiring.

Clearance Clarence. The low pressure at idle after a highway run is telltale symptom for excess clearance at the main and rod bearings. Also you have got lots of BS about filters, all I can say is go get a Wix and a Fram and cut them open and make up your own mind. The guys at ProMax Performance can give you lot's of Pontiac info. but your problem is more generic to most V-8 engines and not just Pontiac.  

Okay well I don't feel like pulling the engine and rebuilding the bottom end right now.  I have a body guy lined up to weld on some new panels and skins and primer the car.  I am thinking I'll replace the oil pump with a Melling 80 psi oil pump.  I am assuming that my current oil pump is a 60 psi unit and probably has a partially clogged screen, it's an old engine...  The 80 psi Melling pump should increase my oil pressure to a respectable level.  Especially combined with a better oil filter and fresh oil.  
1969 GTO, YS code 400, 350hp/445 ft lbs of torque (stock specs), LT headers, H-pipe, 750 Holley 4160, Ignitor II ignition.  Complete Painless wiring.

Also, I have some fuel in my oil still.  The oil is black and smells like fuel.  I am pretty sure it's not running rich.  In fact, it was running too lean unit I backed the mixture screws out just enough to smooth out the idle and improve throttle response.  Could it be that my fuel pump is leaking fuel into the oil in the crankcase??  
1969 GTO, YS code 400, 350hp/445 ft lbs of torque (stock specs), LT headers, H-pipe, 750 Holley 4160, Ignitor II ignition.  Complete Painless wiring.

When you change your oil pump I would run straight 40Wt oil.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

40W even in the cold weather?  What brand?

Could it be that my fuel pump is leaking fuel into the oil in the crankcase??  
1969 GTO, YS code 400, 350hp/445 ft lbs of torque (stock specs), LT headers, H-pipe, 750 Holley 4160, Ignitor II ignition.  Complete Painless wiring.

Pennzoil's always been my thing - except I use 30Wt. Probably doesn't make much difference on the brand unless it's some recycled stuff. Unless you live in Alaska, I'm not sure what difference 30 or 40Wt really makes.

What's your take PM8?  

30wt will work just fine I never use pennzoil I would recommend Valvoline oil.
How cold is it were you are at?
That could be a possibility but a slim one.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

I am in Germantown MD.  It's not all that cold of a climate but winter is on its way.  
1969 GTO, YS code 400, 350hp/445 ft lbs of torque (stock specs), LT headers, H-pipe, 750 Holley 4160, Ignitor II ignition.  Complete Painless wiring.

Straight 30WT Valvoline oil should be fine for the winter.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

Is that better than the 15W-40 Rotella T oil?   I hate to keep switching oil on the engine.  I like to stay consistent..

Where can I get a Mobil 1 or Wix oil filter for this engine?  Advance Auto only has Fram and K&N.  I guess I could go with the K&N, but if Wix or Mobil 1 are better, I'd like to use one of those.  Whatever is best.  
1969 GTO, YS code 400, 350hp/445 ft lbs of torque (stock specs), LT headers, H-pipe, 750 Holley 4160, Ignitor II ignition.  Complete Painless wiring.