There are several separate issues here.
Firstly is the "bias valve" which I presume is the factory fit (on a Sprint) LSV, or load sensing valve, which is situated at the body end of the rear brake flexi hose. These have a habit of seizing in one position which completely negates their purpose. Although the club can supply a seal kit to refurbish the LSV, it's my experience that you'll have great diffuculty freeing it off enough to service it and it won't STAY free for long, even when reconditioned by an expert. If you have TJ brakes on the front, you can safely and comfortably delete this. But it won't affect the quality or feel of the brake pedal, nor will it make bleeding difficult, even if seized solid.
Secondly is the TJs themselves. Because they use a bigger piston in the front calipers (54mm vs 48mm stock) it has a tendency to produce a somewhat "long" pedal. This can be partially offset by using the 1500/1850 5/8" bore rear wheel cylinders. But I find on my TJ fitted cars, that I need to keep the rear brake adjustment (I know they are technically self adjusting, but they never work IME) bang on or the pedal gets uncomfortably long.
Which brings me onto the rear adjustment, if it's not right, you will struggle to get a decent pedal. The cylinder needs to slide easily, the H plates in the handbrake shoes need to be there and not worn, The handbrake actuating arms need to pivot easily, shoes must be in good shape and drums need the rust lips on the outer edges of the wearing surface ground off so they slip over the shoes easily when manually setting up adjustment. The adjustment should be done with the handbrake cables disconnected and only once it's perfect should the cables be reconnected, adjusting the cable length if required. Don't FORCE the cables to fit!
Finally, you have a dual circuit master cylinder. If the car is a series IV Sprint (VA 30,000>) this is correct and the car will also be fitted with the notorious and almost completely useless Pressure Differential Warning Assembly (PDWA) on the bulkhead. This thing CAN make bleeding a nightmare, even when you THINK it's bled, it isn't! Since it doesn't tell you anything you don't already know (it only puts the light on when pressure in one circuit is lost, your foot will tell you that!) it's my habit to delete the troublesome and useless thing. I can provide a delete kit which incorporates a brass 3 way for the front pipes, an inline joiner for the rears and 3 new metal pipes for m/cyl > 3way and 3 way > both front flexis. The pipes are needed because the front circuit pipes on the PDWA use 7/16" UNF unions and I can't get a 3 way piece with 7/16" holes (I have tried!) To replace the PDWA's function, but more efficiently, I fit a level sensing m/cyl cap (a Saab 9-3 one fits) and connect it to the existing wiring, you only need to add an earth lead from the cap.
If your car is pre VA 30,000 and doesn't have a PDWA, ignore the last paragraph!
'73 2 door Toledo with Vauxhall Carlton 2.0 8v engine (The Carledo)
'78 Sprint Auto with Vauxhall Omega 2.2 16v engine (The Dolomega)
'72 Triumph 1500FWD in Slate Grey
Maverick Triumph, Servicing, Repairs, Electrical, Recomissioning, MOT prep, Trackerjack brake fitting service.
Apprentice served Triumph Specialist for 50 years. PM for more info or quotes.