Hi youre veloce shifters, rear and front deraileur would work with an older shimano crank. An older campag crank would be fine but you may get problems with the front mech rubbing the cranks. Using shimano brakes would be fine provided the reach is correct. Shimano make both short and standard reach brakes, campag make short reach only. Tektro make short, standard and long reach. If its an old racing bike, say 80's it will probably take standard reach. You need to measure the reach on your frame. Make sure that either the brake calipers or levers have a quick release. For example campag quick releases are in the lever, shimano are in the caliper. Best to measure your rear drop out spacing, if its 120oln you may need to cold set your frame, 126oln can be sprung to take a 130oln hub without cold setting.