14" Disk brakes

That makes no sense at all. Just because your drum brakes work "fine", that doesn't mean the car could not benefit by the addition of disk brakes. Everybody knows that disk brakes work better, will stop your car in a shorter distance, will not fade with heat as bad as drums, and are, therefore, safer. Yes, drums work fine, but when you add extra "GO" to your car, common sense dictates that you should also add extra "Whoa". And even if the OP does not add more horsepower, adding disk brakes is an awesome safety upgrade. I think @Dan's 72 is making a wise choice.
Yes everyone knows front disc are better, but is he upgrading because the drums aren't adequate there not on par with his driving style, have they failed regularly/once and cause near misses my guess probably not ? Rear disc aren't a needed mod.

If OP just putt around town drums are fine. If he does high spirited driving though the twisty and or long steep down hills with lots of braking then yes, especially if they maintained and not giving the performance needed. But if it's just to do something to the car it probably isn't necessary but it's his money and there's worst things to spend it on.