When you build the engine, and you use assembly lube or good oil, it can have a fairly long shelve life. (I prefer oil)

However, before you start it, fill it with oil and use a drill in the dist shaft and prime the engine. This will move oil throught the engine and to the bearings. Also, move your crank to make sure you get the oil to the rocker arms.

I have had them sit for a couple of years, primed them and then started them - no problems.