Canna see your pics - I don't think you have your photos shared wilth "all".
V8 wrote
1. Hohner GT-2
Those trems do tend to implode after a few years. Cruddy pot metal. ☹ Both pickups are low gauss magnet pickups, so there is no issue with having them close together, just bear in mind that the flatwork on the bottom of the kinman, like most Strat style pickups, sticks out a bit, so the Kinman would have to be on the bridge side (or separated away from the P90 a bit).
2. Hohner Jack Bass
I love mine too and anyway, they are not worth much on the s/h market. Every so often I consider "upgrading" to a five-string, but would miss the Hohner too much. I still want to have a headpiece made to take single ball end strings, but otherwise I'm happy.
The pickups are guitar humbucker size, which limits you to EMG Selects for replacements (the same as are in there now). I had a set of real (passive) humbuckers wound by Pete Biltoft at Vintage Vibe and ripped out all the active electronics. It worked really well, and now covers all bases from crunchy rock to super fat dub. Just contact him and tell him you want Hohner Bass humbuckers and he'll know what you need, or be able to make you whatever you need in the same size (although I wouldn't recommend single coils because of the maple body). A set will cost you about $190 +shipping (about $30 IIRC).
Control-wise, I ended up with a three way switch (Gibson-style type) and two volumes (one for each pickup). I went for two volumes because I run the bass in stereo (each pickup to a different FX/amp/speaker setup), but master volume, master tone would work well too. You have to change all the electronics as the stock (50K IIRC) pots will not work with a passive system.
