To my knowledge, there are no US/English fasteners used in the Lima. Every one is metric, making me think the pulley threads are metric also.
If the bolt does not thread in readily, and the internal threads are clean, 99 times out of 100 it is the wrong thread. FWIW, no one goes poking into the harmonic pulley bolts unless they want to remove the pulley, so messed threads are pretty unlikely, unless the previous owner just did not care. I'm not sure if cross-threaded bolts could be twisted in enough to have a good bite and pull w/o stripping out. As I remember, I didn't use a puller when I did my timing belt, just pulled on the pulley and it came free. Either that or it was so easy to remove I was surprised, and had zero problem. Just didn't stick as a problem area.
tom