If it is in a normal garage that can have a few 40 degree day to day temperate changes, there is probably at least a small amount of rust in the cylinders. If this is just a beater 318 I would squirt some WD40 in the cylinders, prime the oil system and run it. Other wise it may be a good idea to pull the intake and heads and look things over and put some fresh cam lube on the lobes. Since it is on a stand without and coolant in it I doubt flushing it out would benefit much.