Campy Ergo levers can work with Shimano rear mechs via the Hubbub cable routing method. If your left lever (front changer) is ratcheted then you should be able to use any front derailler.

I use a 28 teeth front ring on my Sugino and Deore cranksets of mid-1980s vintage and a 34 teeth low cog on my MTB touring bikes with 26" x 2.125" knobby off-road tires when I ride fire/logging/mining roads and have the bike loadedd with about 50 pounds of gear and food for my 2 weeks long tours. that's a lot of loose surface rocky roads. i doubt you'd need as low a gear as that on paved roads but it'd depend on your level of fitness and terrain you're riding.

I like either Campy Ergo levers (because you don't have to move your hands to shift & because there're no shifter cables rubbing the handlebar bag) or bar-end shifters. Bar-ends have the advantage of a Friction mode which means you can use asny wheel or cassette. Bar-ends are also a lot simpler mechanically.

Cheers