Capri brakes.

The Capri 4cyl master cylinder is shorter than the V6 master cylinder. The reservoir mounts are different too. Girling reservoir is L? 3 the V6 is l?4. The ratio of bias from front to back breaks is different to account for weight. Our master cylinders for V6 had a 50/50 ratio. The South African master had 60/40 and doesn't stop as well as ours. The seal kits for SA and Oz Capris are different. As for internal seals from V6 to V4 they may be the same although the stroke is different which might not affect the overhaul kit but I don't know that answer.
Brakes are one thing you want to get right.
I found this out Bernie as you say sending my boosters in for updating with master cylinder attatched. When they came back the masters were missing and I got sent one V6 and one 4cyl one. I was not happy at all!!

I got my booster changed in the Perana. It has always been known for bad brakes. It came with standard V6 and uprated pads. Perana is only 9kg of extra weight to a V6. I must keep it original though.
So rather than change much their is a company I know and I'm sure others here do that from what I believe put a double diaphragm Volvo set into the original Capri booster increasing it's power. The Perana stops so much more confidently with it installed. It still has the original master (now Oz not the SA) look. The booster is the same look too but it all works better.

Wiggy333
The Capri 4cyl master cylinder is shorter than the V6 master cylinder. The reservoir mounts are different too. Girling reservoir is L? 3 the V6 is l?4.

What's your source for that?  The parts book shows that for the dual circuit systems, the booster, reservoir and master cylinder are the same for all.

Just that booster is the same. The master cylinders different. The parts book refers to 69 and 70. After that the V6 was different. Bore was the same stroke was different. You can't stop a heavier car with the same mechanics. Only my memory and removing a few. I need the newer 71 to 72 parts list to prove it. I may be wrong but not unless many of my cars were messed with.

Wiggy333
 I need the newer 71 to 72 parts list to prove it.

The 11/73 version is on its way Keith!

According to the 11/73 parts catalogue, ALL Master Cylinder Units whether for 1600s (1969-1973) or for 3000V6s (1970-73) were the same unit, ie. 69EB 2140 CA AND, that the Brake Booster Assembly were also ALL the same units, ie. 3040E 2005 BS.
 
The 1600s only ever had 1.5" wide rear brake shoes, ie. 71EB 2200 CA and a 0.75" bore rear brake cylinder, ie. 65BB 2261 AB, whilst the 3000V6s had 1.75" brake shoes, ie. 71EB 2200 DA and a 0.70" bore rear brake cylinder, ie. 69BB 2261 AA. From experience, I was never able to find 3000V6 replacement rear brake cylinder units (0.70") after market, only the 1600 or 0.75" ones.

Cheers Terry. Shows that my 4cyl cars were played with in the past. I was wrong on this obviously. I just wonder how the V6 brakes were uprated then. Was it just Calipers and size of all else was the same.

...................and rear wheel cylinders as detailed above