Oil Pressure problem on 86 F150 with inline 6
I just bought a 1986 F150 with the inline 6. It's my first Ford truck and basically it's going to be a hay and horse hauler. Problem is that when cold, oil pressure is fine, when warm, it goes to low. Does not go back up when revved or when driving. Just stays below the low line, but not quite at zero. This weekend I'm going to replace the gauge with a mechanical one and change the oil since the truck has been sitting for over a year.
There is no knocking sound coming from the lower part of the motor, or anywhere else for that matter. If the gauge isn't it, I'm going to change the pump and probably the main bearings since I'll be down there. From what I've read, this is pretty straight forward. Remove radiator, jack up engine about an inch, prop up, and drop the pan. Remove pickup tube and screen, drop the pump. For the bearings, I read that you can roll the top one out using a pin in the hole on the crankshaft, and roll the new one in.
Is this as straight forward and easy as it sounds? Barring any issues, what's the average time for the shade-tree mechanic to do this in?
Any advice or info would be great.