Originally Posted by
zacster
Somebody here will say to get a Shiftmate, that converts pull ratios from Shimano to Campy or vice versa. It'll work, maybe, but will it work well?
Will it work well? Emphatically yes. I've used Shiftmates to allow 10-speed Campy brifters to work with Shimano 10-speed cassettes and derailleurs and Shimano 10-speed shifters to work with Campy 10-speed cassettes and derailleurs. In both cases shifting was flawless.
If all you want to do is replace the worn out 10-speed Shimano STIs with Campy 10-speed Ergos, a Shiftmate will make them play very nicely together so Option 1 is feasible.
But, as noted, current groups are 11 or even 12-speed and your 10-speed wheels won't accommodate either width cassette so Option 2 will be much more expensive but will modernize the frame as much as possible. Current Shimano brifters have a somewhat longer brake cable pull than older groups so your current brakes may not work as well. AFAIK, Campy hasn't made that change so your brakes should be ok but check on this.
Disc brakes and thru-axles will obviously require a completely new frame and fork and are beyond the scope of your questions.