If it’s a 700c frame and wheels all you need is pretty much any road brake caliper. A dual pivot performs way better than a single pivot. If you’re on a strict budget single pivot will most likely be cheaper.
My choice for calipers is Shimano 600, RX100 or Ultegra - excellent brake and the 600s and RX100s are relatively cheap used. Campag ones are just as good but Shimano have the quick release on the caliper which is handy if you’re using CX or BMX levers.
Also, both a front and rear caliper will work on the front. You just need to change the nut to switch between front and rear because the rear one has a shorter bolt. The nut you need can be bought easily at bike shops for a couple of bucks.