Read my reply.
2200 - 2800 RPM is ideal for the 6.2L. It will put out most of its power in this range, and will run happily all day at this speed.
An elevated tank will offer the best protection against contamination (second only to underground storage), and eliminate the need for any fuel lift pump. Priming is as simple as opening the fuel valve. Otherwise, the engine will have an engine driven mechanical fuel lift pump, mounted on the engine in the same location as any typical older GM V8 (which should be bypassed with any other positive fuel supply). With no positive fuel supply (ground level tank), priming will require extended engine cranking, or another pump to lift the fuel prior to start (IF the fuel line was allowed to drain dry, which is a BAD thing). The engine should be shut down with the system full of fuel. Draining the system will lead to serious problems the next time you need to use it. You will need a dedicated high quality fuel supply filter system, so select one with a manual priming pump, and that should solve that.
These are also called "Murphy" switches. Read above. The fuel injection pump, in OEM form, requires 12V to the pump to open the fuel to the pump. Your existing Murphy system will swap over without any modification. There are plenty of taps for oil pressure and coolant temp.
That's why we're here. That's what we do. Keep it simple. There's nothing complicated with this. I also suggest an oversize oil pan. The original 7 qt. volume is marginally sufficient for stationary use. Make your own (simple, since you have no vehicle limitations), or buy one. Most of what you need can be had from
www.peninsulardiesel.com . They deal primarily with marine applications, which is essentially what you are building.