You will probably have a engine knock if your rod bearings are bad. What you could do is pull the spark plugs out and on the cylinder you are checking rotate the engine until that piston is on the down stroke stick a screwdriver down the spark plug hole and gently push down on the piston and if you feel it give a little then that could mean you have bad rod bearings. If they are good and you have an engine knock then it could possibly be piston slap or you have bad crank bearings.
this enging sat for about 3 years and i know the p/o did not fog it. are the wrist pins more prone to failure or are the lower con rod bearings? no knock, slight quiet rattle at idle, starts right up, idles perfect. (2000 polaris xc500 w/ 1900 miles)
In that case if u are worried about the lack of lubrication from sitting you could hold the oil pump in the wide open position the next time u start it just to give it a little more oil or possible run a little premix in the fuel tank. Just make sure u have all the old fuel out of the system. Since there are no real signs of engine issues I would do one of these and hope for the best.