Both the AVRI and the Japanese reissues have the god-awful bridge. As far as putting a tune-o-matic in goes, there will be a fair bit of tweaking to do. The bridge post holes are in the right place, but you'll need to wrap enough insulation tape around each post to make a smooth push-fit into the thimbles, to stop the whole thing from rocking about and spoiling your set intonation. The tape mustn't be too close to the end of the adjustment screw because it may insulate the bridge from the ground wire and cause grounding problems and interference. Also, the extra height of the tune-o-matic may require you to shim the neck slightly. Finally, because the T-O-M is designed for a 12" radius fingerboard, the saddles for the top two strings and the bottom two strings will need to be filed deeper to fit with the tight 7.25" radius of the Jazzmaster. The best solution for me is to replace it with a Mustang bridge. Absolutely ultra simple fit, doesn't change the tone of the guitar at all and works well with the tremelo system.
I really like my Jag - it has an absolutely wonderful sound, but if you want to shred or you play lead a lot then there are much better guitars; sustain isn't fantastic because of the low break angle over the bridge dissipating some of the energy of the string, and heavy string bending on the plain strings high up the neck can cause choking off of the note because of the tight radius. You need to set the action slightly higher than you might on an L.P.
