The Jagmaster has a standard stratocaster "Swimming pool" route (at least the newer ones do). To install Jazzmaster pickups, one would have to do some minor routing, plus add some wood for the pickups to screw into as the cavity is a little deep for Jazzmaster pickups from what I have seen.
On the other hand, Jazzmaster cavities will fit Humbuckers, but if you use something like a PAF where the screw connectors go an extra 4th of an inch downward or so, you'll wind up cranking the bridge up pretty high and shimming the neck a good bit for the strings to clear the pickup.
