There are people who have drilled the Campagnolo Nuovo Record spiders for triple rings, and I've thought that would also work on the flat Dura Ace spiders.
However, the Willow type triplizers should also work without modification of the crankset.
Shimano 6703 triplizer parts are also still available, but would require machining off the shelf for the inner ring.
Hopefully your front shifter would be agreeable with the triple, but I doubt the front derailleur would be.
If you upgrade the derailleur, look for a cyclocross style triple derailleur. DO NOT USE A MTB DÉRAILLEUR. The MTB Dérailleurs sit too far behind the seat tube.