are you sure you have the timing light on the right spark plug? being off by 2 inches is like really a lot. You have had it 11 years, and you never checked the timing? Did it ever run right? You could have a different timing pointer than original (it was a rebuilt engine, right?) or like the fella said the balancer rim may have slipped around, in which case you should make sure it isn't about to fall off. There is something missing here. I have no idea how you would "guess" the timing. I would set the static timing to begin with and see where you are at that point.
