Right Im going for the Datsun 1200 hubs and Sigma GE caliper and rotor setup again
as its what I know how to do but just wondering if there was a better MC than the
datsun 1200/120y early with only a single filling reservoir or twin external reservoirs?

Any
Just make a pushrod to suit
I'd go with 3/4 or 13/16
You can fit those remote tops to the 2 first cyls too

22mm is 7/8 not 15/16"
 
I wouldn't go 7/8 unless youve got big legs
My car has 13/16 and I'm 120kg...I like it... but it takes alittle effort and I like a high pedal
For most people I use and recommend a 13/16 (20.64) and the lightweights use a 3/4
 
The Nissan ones are easier cause they bolt up straight to the firewall... but if your hiding it the mount really doesn't matter
You can get plastic adaptors to suit that one with the resi on it so you can delete the bottle and mount it remotely

Bigger cyl needs bigger legs... or a booster
13/16 is more than enough
7/8 is a noticable increase in effort and firmer (less travel)