The bean-can spinning speaker system is called the Spectratone, ingenious little things. If it's like my dad and my Spectratones (we've got a 420 and a 500), it's one speed. I have seen a motor that looked a lot like the two we have, and it had a slow motor, but I'm not 100% sure it came from a Wurly. Check, does it have a little thing hanging onto the bigger motor? Also, look for an O-ring that the little thing touches. That would be a second motor.
Call up Morelocks Organ service. They have schematics and parts for a lot of this stuff, if not all of this. I got a 420 schematic (and extra Spectra belts) from them for pretty cheap, and it's helped me immensely. I even made my own 6W (147-style) to Wurly 420-style connector so I can hook the organ to it. As for guitar, it's not too hard I think, you just need a pre-amp-in or a power-amp-in (with a load resistor). You just need to know which pins go where.
Please please please don't gut it to make it into a guitar thingy, there aren't many of these left (at least compared to Leslies). It's not hard to make a connector box for 1/4"-in from a $5 Radioshack plastic project box Jan Giradot seems to have a lot of knowledge on these things, and I've been digging around in mine for a while so I can try to help if needed too