Fastman, here is what I know about the Volvo option.
Master Cylinder:
Can not suggest which master cylinder to use but logic suggests that you use the one off the car that donated its callipers. I am told that you need need a master cylinder with a bigger swept area to move the extra brake fluid needed for the 4 pots. Mk1 SD1 Rover seems to be good and keeps your car looking original...sort of.
Callipers:
Volvo 240/260 callipers (Australian Models) - two types on these cars, Girling (22mm Disc's, 1976 to 1993 model cars) and ATE (24mm Disc's, 1975 to 1993 model cars) use the ATE Callipers. Calliper mounts have to be modified by drilling the bolt holes slightly wider to fit the TR (Plug and then drill). Convert the dual pipe inlet to single by either cross drilling or use this EXCELLENT kit:
http://www.mildevco.net/chevypowereddat ... brakes.htm
The rotor used by Triumph Rover Spares in South Australia is Part Number DBA-631-MB 19/6/96-MINTH 18MM-2N. (DBA = Disc Brakes Australia) This vented rotor is found on Ford Courier/Raider 1985 -1995 models with 1.8, 2.0. 2.2 and 2.6 2WD motors. Also On Ford Econovan/Spectron 1984 - 1992 with 1.8, 2.0. 2.2 motors in STD and LWB chassis. The standard TR rotors are 240mm in dia and these are 256mm in diameter, they work with the new callipers.
You need to make up a bell to mate the new rotor to the calliper.
Piston Diameter stuff:
Here is part of a spread sheet I have made up covering piston diameters. First column is the calliper known by the car we take it from, second is the dia of each piston, third is the number of pistons and final is the culmulative total of piston surface area in mm2 used to exert force in a calliper.
TR7 51 2 4086
TR8 54 2 4580
Princess 38 4 4536
Volvo 38 4 4536
Capri 54 2 4580
Hi Spec Motor Sport Ver 1 38.6 4 4681
Hi Spec Motor Sport Ver 3 41 4 5281
Vitesse 41 4 5281
NB: Note that Volvo is pretty much the same as a genuine TR8 calliper.
This of course does not take into account the extra leverage you get when you stop a 256mm dia rotor versus the 240mm rotor. The radius or leverage is longer therefore more force is exerted that way as well. I am not an engineer and would enjoy someone adding precise maths toall this data.
Yes, I love talking about 8's Hasbeen.....does it really show that much.... Chuckle.