Sorry but I really can't advise you on this particular job. And when you say plaster, I'm figuring you don't mean drywall. (Some folks have been known to interchange the 2 ...)
Anyway, what I want to say is that before you get too far, at some point, you've picked a spot where you want to put the cabinet. Before you buy and before you cut, make sure the cabinet can fit in the 'rough' opening. You see (if you don't already know), that the studs used for plaster and lathe walls may NOT conform to 16" on-center standard of today. You will be OK if the rough opening is more than 16" but you may NOT be if it's less. You may have to have one custom-built depending on the opening.