Cortina Mk2 brake master cylinder

[Aus911]

Hi All,
I have a 1968 Mk2 Cortina with the single line master cylinder. I have seen what looks very similar to mine advertised for the Mk1 Cortina.
The one I am looking at is P4979. The data shows the correct 15.87 bore but I am not sure about the port size, or the mount offset.
Does anyone know if the brake master cylinder used on the Cortina Mk1 is the same as the Mk2 single line brake master cylinder??
Has anyone used a P4979 MC?

For interest my master cylinder has:
* A bore of 15.87 mm (5/8 Inch)
* The port is 3/8 24 UNF
* the mount is 2.25 inch (57.2mm) centre
* The body length from the mount is 115mm
Thanks in advance
Ray