You can disable the ignition coil and crank the engine until it shows
something on the gauge.
That would be the same as turning the engine over with a socket and 1/2" ratchet.... But much more effective.
There's definitely no downside to priming an engine, but it is likely to build pressure before it fires, after half a year.
Just make sure your battery is in good shape, and have a starter/booster if needed.
Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.