Disc brake master cyl bore size.

yes and yes
If it bolts on, and has room for the pushrod, it will work.
The smaller bore will travel a little further, but will be a little easier to push and modulate. It is what I use.
If you like a hard high pedal, the bigger one is your guy,
Having a Residual valve is a bonus, for the rear drums
If one of them has 2 similarly sized chambers it came off a drum/drum car.
If one of them has a larger chamber, it is designed for a disc front car.
If one of them has a screw retaining the guts its is an older design.Later types have a circlip retaining system.
Bail-wire or screw-top, your choice.
Be sure to bench-bleed the M/C before installing it, and
Be sure all your brakes are adjusted close to correct before commencing the bleeding, it will make it easier.
Don't forget about the pushrod adjustment; it has a narrow operating window.Better a tad too short than too long.