Hi Mettlen,
As you know, I fitted that engine about 15 years ago, and I doubt it has run much since, knowing where it was, that is not to say it has suffered too much, if it turns over and rings have not rusted in the bores, then it should be alright, unless any exhaust valves have stuck. what i am wondering, about your spark plugs is did you release the smaller hexagon on the plug, leaving the outer shell? If you use a normal plug socket for 14mm spark plugs (7/16" Whit deep socket) there should not be a problem.