Crankset Upgrade
 

So I've got an early '00s steel race bike that's been pressed into service as a commuter (I know, I know, but it gets the job done); I rode through the last winter on it, and as the wet season approaches again, I've begun to consider upgrades. The whole drivetrain is Campy Xenon, which I don't love but is still largely functional. However, having spent a season slogging up hills with it, I'm thinking about changing out the 53/39 square taper crankset for a compact; I've already got a hollowtech BB in the parts bin, so I imagined I'd just pick up a cheap Shimano compact double when one shows up on sale. This relies on a couple of assumptions: first, that the Campy FD and left shifter can be adjusted to work with a Shimano crank - I believe they will work just fine, but don't actually have any confirmation of that; and that the inboard/outboard position of the chainrings won't be drastically different between the two crankset/bb combinations and screw up the whole chain line.

Is this reasonable to attempt?

The Campy ft shifter not being an indexed one has a lot of compatibility in it. I would (and do) mix ft system parts when using a Campy ft ergo shifter. As long as you don't use the extreme cog/ring combos the chainline issues shouldn't be a problem. Andy.