I really don't think there's a market for it though and if there is, it's very limited. Even TVR use Ford fuse/relay boxes!
For the majority of rewires, I use two of these from
www.vehiclewiringproducts.co.uk
Why two?
One fuse box is permenantly live, the other is only live when the ignition is on. Makes the wiring much easier to understand that way and the second fuse box is triggered by a high power relay so the 30+ year old ignition switch doesn't have all that current running through it!
In my opinion, the stock VW wiring system is flawed in a few areas. I hate the way one fuse is connected to two or even three circuits. I also hate the fact there's an unfused wire running directly from the battery, along the heater channel, up the inner wing and behind the dash to the headlight switch and THEN to the fuse box. Do a bit of welding on the A-post, inner wing or seat runner and before you know it you've got a bare wire touching the chassis.