Starter issue

[Tomahawk30]

Having some starter problems in the 72 Cheyenne K20 I brought home today. I've done some searching and found similar issues, but I haven't found one that describes the same thing exactly.

Brought the truck home today with no problems at all (except the really bad exhaust leak on the driver side manifold where the manifold connects to the pipe). Got it home, unloaded it and shut it off while I wrapped things up with the trailer. Fired it back up to go for a spin, but the starter kept spinning after it disengaged from the flywheel. I shut the key off and the engine died, but the starter still kept spinning. I ended up pulling the battery lead to get it to stop. Now if I try to reconnect the positive lead, there's some pretty healthy sparking going on.

My first guess thought is a short on the ignition switch to starter wire. I couldn't see anything obvious, but it was getting dark so I didn't spend a bunch of time on it. I've also read that the solenoid could be stuck in place so the circuit is kept intact. Would that cause sparking when i try to reattach the positive lead even with the key switch off? I'll do some additional troubleshooting tomorrow when I have some daylight, but thought I'd see if anyone has any ideas.