Ah, well one piece of info I forgot about was that the previous owner of my bass had swapped in a 90s-era hi-gain into the neck position. There are two raised ridges in the black plastic molding around the pole pieces, which were not added until the 90s, so that pickup is probably around 9-10k. Still not as hot as the current ones, though, which are really quite beefy! I'd say, too, if you are just looking for some more top end/bite in your 4003 (I assume you own one and are contemplating a pickup swap, based on this whole chat?), try putting in higher value pots on the neck pickup; they are usually around 330k on today's models. Maybe 500k or even 1m would open things up more for you? Way cheaper than a toaster, that's for sure!
I'd have to say that there wasn't a huge shift in sound from the hi-gain to the toaster; it's definitely got more treble response and clarity, but it's also quite a bit lower output! I was deliberately going for a small volume mis-match though, since I wanted the bridge to overpower the neck when using the middle pickup position.
I'd say that if you haven't heard from me about the pickup recording by early December, shoot me a PM, and I'll be sure to make it!