If you fancy doing a Campag build , and you should, I would strongly recommend using Chorus or above for the shifters , the lower versions don't shift as well and wear out a lot quicker and when they start wearing the shifting becomes woeful no matter how you adjust them . As for the derailleurs anything Veloce and above is fine , just make sure if you're mixing and matching models/years that they're fully compatible .
So following my own advise , I've fitted Chorus shifters , veloce front mech and an Athena rear mech , all are pre 2015, and 11 speed, so will work together.
The difference between getting a snappy gear change or a mushy lottery of a gear change usually comes down to attention to detail.
First off , the gear hanger has to be perfectly straight , I checked mine and it was perfect , this in my experience is unusual , they nearly always need a tweak ,even on new bikes, I guess Ti doesn't bend easily.
Cable choice and fitting is crucial . What you are aiming to do, is reduce friction as much as possible . For inner cables I use and recommend Elvedes slick stainless , and for outers,Jagwire 4mm . You need a nice smooth cable run, on this bike I ran the cable along the front of the bars , then crossed cabled , this gives a nice wide radius arc.
Right, attention to detail stuff; Before threading the gear inner into the shifter I always put a bit of grease behind the nipple , this is a bit old school , supposedly helps stop nipple snapping off , won't do any harm anyway. After cutting the outer cable to size , it's good practice to file the ends flush , this can help reduce that mushy feel. I don't like plastic end caps , I really like the CNC machined alloy ones that Clarks have brought out , when fitting these I put a dab of grease inside to keep things running smooth, and more grease on the outside so they don't seize in the frame.
As my frame has no downtube gear adjusters , I've added an inline adjuster for the front mech , not strictly necessary, but will make cable tension adjustments much easier. Lastly I added a seal at the rear mech cable stop.
Forgot to mention , I've fitted a KMC chain , the basic model, they work really well and don't break . I'm running a 12/28 shimano11 speed cassette, I've never had a problem getting these to work with Campag .
Now the final adjustments , starting at the rear mech . Firstly I set the high and low screws and then , and this is a pro tip , with chain on 1st gear with the pedals turning I give the rear mech a push to see weather it taps the spokes , if it does screw the set screw in till it doesn't , likewise run the chain across to top gear, then gently tug the rear mech whilst turnng the pedal , if the chain starts to come off and jam into the frame screw the set screw in a touch , I always to this on every bike, saves a shit load of trouble. To index the rear mech , run the chain onto the 5th sprocket and turn the cable adjuster until the jockey wheel sits directly under the sprocket , now drop the chain down to the 11 th sprocket , and give the inner cable a bit of a yank , now go back up to the 5th sprocket you'll probably find it needs another half turn. Make sure the adjuster barrel isn't screwed out too much , they can snap off easily if they are. It's also possible to adjust how close the jockey wheels are to the sprockets , should be 5-7mm , put the chain in 1st and measure , They'res an adjustment screw below the lower knuckle , I set mine at 6mm.
I fitted the front mech with cage 3mm above the outer ring and with cage straight with the ring.
Next put the chain in 1st gear on the small ring , adjust the lower screw so the chain just doesn't touch , then put chain on the 11th sprocket at the back and the big ring and adjust the set screw until the chain just doesn't touch the inside of the outer cage plate. Finally I tension the cable by the putting the chain on the small ring , and this is where the inline adjuster really helps, and tension the cable to the point where it starts to move the front derailleur as soon as the shifter paddle is touched.