Storing an engine
 

No different than storing a bike long term.
Ideally it would get a fresh oil change, so much less combustion byproducts, contaminates, moisture, ect are left in the motor.. as its not running..that is an issue. but see below.


Remove the plugs, and fog the cylinders, rotate motor, fog again, replace plugs
After draining the oil, fog the motor, spray in the oil pan drain, the oil fill, remove the valve covers and fog all openings into the motor case...Basically spray figging oil in every opening you can in the motor.
Ideally the cooling system would have been flushed of the old contaminated stuff and a no silicate coolant in the proper mix circulated just before storage.

I would likely try that on a out of frame motor as well.... drain what you can, use a hose and bucket to catch coolant from the pump output, and a hose, funnel to gravity feed a gal of coolant though the motor, and do that a few times in effort to flush old coolant and coat surfaces with fresh... I would then plug pump output, "fill" the motor as best i could with fresh coolant and plug the pump input.
Make darn sure the coolant is mixed well if it was from a concentrate (one of the reasons id flush at least 2 times ) or better, use a pre mix coolant... you dont want partial mix water/coolant to remain in the motor