Which master cylinder????

can anybody help?
im in the middle of upgrading the servo and m/c on the mk1
i already have the 9" mk2 16v servo….is there any reason why i cant use the 22.2mm m/c rather than the 22mm?
any advice would be greatly appreciated cheers!

No same shape and size from VW parts bin .......Just make sure when you have both in your hand that they are matching in apperance . Shape and size .