Blend: ASS4003 Neck and ASSY HB1, Best wiring? Need help

[visualfuzz]

Hi,
My bass player get a Custom Bass with Rickenbacker standard ASSY 4003 Neck Pickup and HB1 on bridge.

He want a specific wiring: 1 volume control and 1 blend control (to change between the 2 pickups) and no tone pot.
Actually I put a 500K pot on volume and a 500K blend pot.

I don't think I'm correct in values, what I read it's the original Rick bass have 250K on volume and 500K on tone. After in 90's, they put 300K on each controls.
Actually, I find the sound of the bass really trebly and missing a bit of low end. About what I read here, it's the choice of the values are crucial when you use blend.

What can I use to get the best of the pickup sound?

Thanks a lot for your help.

[vax2002]

Having messed with all sorts of pick ups, nothing beats the hi-gain stocks to me.
Yes you might get a bit more output, but the magic is in those pick ups.

[loverickbass]

I've got the opposite. HB1 in the neck and higain in the bridge. I had Dane Wilder make me a custom harness. The new harness is OK, still not enough treble though.