Brakes from that era generally aren't too good. Cheap upgrades are Kool Stop pads, cable & housing or lubing existing inner cable. For a quick help pull the existing pads and sand them down to get past some of the hardened outer surface. Aero levers will help. It appears that at least you have Al rims and not steel which no brakes work good on.

Double pivots will be an upgrade. You then will most likely need the Aero levers due to cable pull issues. If you have 27" tyres you'll need to check reach length as new ones are for 700 tyres usually. It would be good to check reach anyway. You'll also most likely have the problem of your current calipers being nutted and the new ones recessed. This will require the drilling out of the back of the fork and rear of the brake bridge to accomodate the recessed nut. Not a big deal, but a pain on the rear brake bridge, as you can't fit a power tool in there and have to do it by hand.