What have ppl used? I'm watching this Bias on eBay as the time is near for me to plumb up all my brakes and handbrake! I need something not to big as I ain't got a lot of room to fit it anywhere! Lol
Also should it be fitted b4 or after my hydro handbrake? Any ideas?

I would have thought before.

A lot of guys here use a Volvo adjustable proportioning valve from the wreckers.

i would put it in before hand break but put it where you like and its reachable. Once set you wont need to change it often if you stay on the same surface.

you can also use the one fitted to centuras, or to 'original' minis.

It's probably worth noting that these aren't a true proportioning valve, The proper ones will alter the relative amount of force given to the front and rear circuits - the harder you press the brake pedal, the higher both pressures go, but one will always be proportionally higher than the other.

The valve in the link, and the ones on minis etc, aren't a proportioning valve. they are a pressure limiting valve. Basically once you dial it in, the harder you push the pedal, the more pressure to the front brakes, all the way. but at some cut off point, once the rear pressure reaches a certain level, it will shut the valve and prevent the rear brake line pressure going any higher.

In practice they still work exceptionally well, even on a race setup. (obviously if you want every last bit out of the brakes, a true proportioning setup is required)

HOw does the hydraulic handbrake work? I've never actually seen one in the flesh, but the ones I've seen in a car (that I couldn't pull apart!) had it routed to a pair of separate smallish calipers on the rears, so that it would function 100% independant of the normal brakes, and was used for sliding the rear around.

If it routes into the existing system, what does it do, close off the port from the master cylinder line that goes to the rear (so the fluid isn't just bled backward into the master cylinder/reservoir) and apply it's own pressure or what?

also - I've got a centura one here (and likely a mini one too) you can have mate.

All of the hyd h/brakes I have seen/used were Hillman Imp master cylinders and just inserted into the rear line.

Acted as a pass through normally and then applied pressure to the std rear brakes when yanked on.

Could also use any remote vac booster master cylinder as they do exactly the same thing.

mine hydraulic handrake is running through main line, yeah it's supposed to block off whatever it has and pump those lil' drums like the buggery but in practice it's kinda lame cos I've gained more travel in the pedal. I'm guessing it needs a better bleed but I also have a stanza master to go in as I've been informed they should match up well to the front and back when I put those disks in