I have a Jaguar Bass humbucker and calipers in my hand as I type this. It is epoxied. It does have large ceramic bar magnets attached to the bottom of the large polepieces. So it is an aggressive pickup. The pickup seems to be right at 1.5 inches wide at the bottom of the pickup, its widest point, and a shade more than 3.5 inches long. So any "35" style soapbar should fit.
Of course, the most famous soapbars are the EMG actives, which are engineered to have an even higher output than the Jaguar Bass passive humbucker. The EMG HZ's have a little less output, but many think the tone is only average. I like them, and have them in one of my basses, and they seem to be of a moderate output overall, a little bit middy in character.
Since a "35" style soapbar will probably fit, it may be time for a pickup safari. Bartolini pickups are known for having great tone, but not necessarily a high output. They make an M34 series that has several models of different tones, including the M34CBC-T, with "bright treble"; maybe one of them will be to your liking. The folks at Bartolini.net would be happy to advise you.