Bicycle Mechanics - V-brake interchangeability?

I'm asking this on behalf of my dad, he's looking to do some brake swapping. He's got a fairly inexpensive bike which has served him well for several years with one exception - the brakes. While they have always worked well, the little tension adjusters are made out of plastic, and one of them will crack and break open once every couple years or so. So he's looking to upgrade. I've seen some Shimano Deore V-brakes for $30 a set, and I'm thinking these would work fine for him. My only question is, how do we know if they'll fit his bike? Are the cantilever studs the same? How about the distance from the stud to the rim? I'm not seeing much in the way of specs and measurements on any of the websites selling brakes, which leaves me to assume that they're mostly universal. True?

Shimano canty's - right? those little plastic spring retainer things crack. You can jury rig them with a zip tie to hold it together, but Shimano will send replacements to most any LBS at no charge.

V-brakes will bolt right up to your canty studs, but the cable pull from your levers will be wrong so you'll need new brake levers too. If your brake levers are one piece with your shifters you'll have to replace them also. Isn't upgrading bikes fun?

Nah, he's got some v-brakes already. He has gotten the replacement part for free a few times too, he just wants something he doesn't have to deal with now.

So canty's are swappable too huh? I didn't know if the canty stud location would be the same. He mentioned wanting to upgrade the "lame brakes" on his wifes bike, I imagine she has canti's then. I'll have to see if her levers are integrated with her shifters.

Thanks for the quick reply.