Re: whos good with jacksons? trem question.
I know you can just drop on OFR in place of a JT500 because I've done it. The thingies that the fine tuners press down on at the back of the baseplate - whatever they're called - come out a tiny bit further than the trem cavity, that's the only thing. I just hacked away at the cavity a bit, because my Jackson is was all dinged and scratched anyway.. if you have a pristine instrument and want it kept that way, there might be a more elegant solution.
I've no idea if the JT580 differs at all in its routing template.. the only difference I'm aware of is the angled baseplate.
BTW, so long as you're not planning on getting the money back in resale, putting a genuine floyd in is a great move. Those lic floyds are the only thing holding a lot of MIJ jacksons back. They tend to wear out with use.. mine did anyway.. and not hold tune anymore. And the difference in tone with the upgrade is like a whole new guitar..