You got me with this one. last engine I had the would only turn about a half turn had a very bad bent push rod. As soon as the cover came off it was clear to see. Only a few things can hang up the bottom end like what you have, one of them is a rod hitting the cam shaft. Wrong year cam could do that. Another thing would be a bolt catching the bell housing. That is tough to catch until you actually see it happen. That is about it. If the dizzy is still in place you could have an issue with the oil pump, but what ever it is you will find it on the stand for sure. Let us know what it is. Curious minds would like to know.
