Respect for showing your error, you could have so easily pretended it hadn't happened! The standard clutch master cylinder size is 5/8 but the 3/4 one often gets fitted as it is easier to source. It seems to work albeit with a heavier pedal. I think the green wire may be for the handbrake warning light on the dash? I would retain the Girling slave cylinder just in case as some of the repro parts can fail, you may be better off putting a kit in the genuine Girling one. Hope all goes well!

Top tip - carefully wipe your black rocker switches with a little brake fluid. They come up like new. Stick with it.

Nice Job...one for your engineering dictionary boast fork on cylinder is clevis and pin

Apologies for ridiculously suggesting you rebuild your clutch after the gear oil debacle! In my defence, it was sage advice. If time travel were a thing. I keep forgetting your early stuff’s two years old.