I don't understand the advice to not use a high volume pump. It supposedly increases low rpm oil pressure because it pumps more oil without increasing higher rpm pressure because the relief spring relieves at the same pressure as a standard oil pump. Sounds to me a HV pump is exactly what you need. Replacing the pump with a standard pump may not do anything to increase the oil pressure at idle.

 

Quite simple if you think about it. It would be about the same thing as replacing all of the main and rod bearings but not replace the rings. Because the bearings are now tight, a lot of oil is being sprayed on the cylinder walls and bottoms of the piston. New rings will have sufficient tension to wipe the oil from the cylinder walls. Old rings with over 100,000 miles on them most likely won't have the tension left in them due to wear in sufficient amounts to wipe all of the oil from the cylinders. You will have built an oil burner. The high volume pump in a worn engine is the same thing. Because of the volume of oil, you'll have oil being sprayed in large volumes on the cylinder walls and rings most likely with not near enough tension to wipe it.
Usually if the pan comes off, it's real easy to rebuild the lower end of the engine. It's just a matter of pulling out the old and replacing parts. So installing a new lower end is just a matter of cost and labor, not any major extra work. But in doing this, you'll end up with a highly likely oil burning engine as the oil volume, not pressure, is more than tired rings can handle. Ever have some one do a valve job on a high mileage engine? And then you have issues all of sudden with oil being pumped out of the PCV? A high volume pump is like that on an engine having 100,000 miles on the clock. What fixes one problem causes another problem.
High volume oil pumps are good for most rebuilds but they can cause more problems than they are worth on any engine with 100,000 miles on the clock.

 

If you are going to pull the intake manifold it's going to be tricky to jack the engine up the 12" to get the clearance to get it out. If you are only going to drop the pan but not remove it, you won't have to move the engine all that much to get to the pump. You'll just have to work around the pan. A lift could be helpful although my arms don't like reaching up all that much. My preference is to work from the ground. BUT, it might also be cold where you are now and laying on the ground not a good thing. If the lift does not include lifting at the wheels but by the frame, I'd skip the removing the intake and just work around the pan. Once the pump is off, you can remove the pan for cleaning. If you find a bunch of sludge and crud in it, know the rest of the engine is also sludged. Cleaning the internals will probably bring issues and if sludged, I'd budget for a rebuild next summer.
Because you don't have a ton of money in this truck, this is a great platform to learn how to do mechanical work. It's relatively simple, for the most part easy to work on, simple enough to learn by, and there's a buttload of parts available, new and used, that are not expensive.

 

 

To connect a mechanical oil pressure gauge, remove the oil pressure sender and use the appropriate adapter to screw the gauge line in.

 

That makes sense if the HV pump also increases running oil pressure. I have no personal experience with a HV pump but I thought the idea behind it was to better maintain the same pressure of the stock pump. Any pump will maintain pressure at higher rpm.