Guys forget all about soaking in engine
oil etc this is what you do. Get online and research Vapour Corrosion Inhibitors, its what all the auto manufacturers use. There are a number of companies which supply VCI coated or impregnated bags large enough for your engine, "Zerust" being one.
My company based in the UK, Carrs Paper, supplies VCI paper and laminates to most of the major auto and auto component companies throughout the world but as yet we dont make the bags...however watch this space. We also supply Rolls Royce jet engines with their VCI protection so we have experience in the aero industry.
If the bags are good enough for the US army to mothball complete tanks in and not worry about corrosion, even in the gun barrels, storing an engine in a decent weather proof environment like a garage should be a piece of cake.
If all else fails let me know and I'll dig out my info at work and point you in the direction of a supplier/stockist.
FYI most of the VCI film we supply goes to companies wrapping bare steel coils which are then shipped overseas without any rusting problems.
What could be easier than putting the engine in a plastic bag..and when the time comes to get it out theres absolutely no cleaning off required !!
Cheers,
Tony