Steps 1,2 & 3 good.
Do not touch the injectors, do nothing except get fresh diesel to the injector pump and bleed the pump.
Turn the engine over with the decompressor pulled until the oil pressure guage moves. Shut off decompressor set throttle to full and see if she starts most will start within 10 to 30 seconds if not bleed at injectors by cracking the pipe nuts while cranking and try again.
Have someone at the throttle to pull it back when it starts.
I have started a number of engines that have lain untouched for years either in scrapyards or in military stores and have NEVER had to overhaul injectors, thrown away a couple of seized ones yes but overhaul no.