So tonight I weighed the bike as a starting point. Totally non-scientific using a couple of cheapo bathroom scales, but it will do for what I need. It was 240lbs on the front and 265lbs on the rear. This will give me an idea of how much weight gets removed/added.
I also ran the bike for a couple of minutes, but it rattled quite a bit. I don't think I'll bother putting any effort into the motor, I'll just sell it as is. So next step is to remove all the junk I don't need and weigh it again.