Steve,
I think the most important issue is where you are going to store them. I have some blocks and cranks at the shop that I have had for at least 10 years. They were cleaned in our oven and steel shot blasted so they are perfectly clean bare metal. They are in bags with maybe a light coat of WD40. They still look like the day they were cleaned.
The key is temperature control. We keep the shop at around 75 degrees year round. If the temperature does not change a lot, they will stay like new forever. If you put them in an unheated garage its a different story. They will turn to rust in a few months
So, if you can keep them in a basement you should be ok. If they are going to be in a garage or shed, then load them up with WD40, coat the cylinder walls and other machined surfaces with engine oil and you should be ok for a couplt of years. Just take a look at them every once in a while.