resurrect a Bosch PSB fuel system

I recently bought an Oliver Super 88 Diesel that was in either a state of disassembly or reassembly and someone had passed away or just given up on it probably 20+ years ago. Initially was going to part it out but after looking around I realized nearly everything was there just needed some love and attention, missing a radiator, PTO clutch and shaft, and front side curtains but otherwise complete. The engine had all the ancillary parts removed and had a lifting chain attached. Out of curiosity I pulled the cylinder head to find a new set of pistons, rings, and sleeves. Fresh valve job with new guides and my son thinks it looks like new intake valves.

Bosch American PSB pump and injectors had been sitting on the bench for as long. Injection lines still attached to pump but injector ends had not been protected and have dust and rust on them. Injectors were not bagged or protected either so are covered in dust and surface rust. I know enough to not just start cranking on the drive gear and try to turn the pump over and break the plunger. Besides the screwdriver test for checking the metering sleeve how to I determine if the plunger is stuck and if it's safe to continue cleaning this stuff up and reassemble to try to start it? Would rather not spend a ton off money right off the bat to send it off to a pump shop to rebuild. Obviously someone thought highly enough of the tractor to invest in an overhaul of the block so I suspect there was nothing wrong with pump and injectors before it sat.

Would like a list of steps to resurrect this engine and fuel system with least cost and not break anything.

The screwdriver test to me is useless, it only tells if the metering sleeve is stuck or not. I can free up a stuck plunger, if pump has NOT been turned before I get it. I
just pulled a PSB head this week to free up the stuck plunger/metering sleeve. Still won't know until the repaired pump is on the test bench whether the head is any good
or not far as passing the low speed crank delivery test..

I haven't even tried turning. Is there a way to determine if plunger is stuck without totally disassembling?

I consider EVERY PSB pump that comes in has a stuck plunger unless it JUST came off a running engine..

What do you charge to go through one? I have no reason to believe there was anything wrong with it before it was taken off. They did all the machine work on engine with new sleeves and pistons. Just never finished putting it back together.