I have been riding Campy almost exclusively - since the 70s.

For a 1988 vintage bike, you could do no better than Shimano 600; in terms of functionality it is far better than anything that Campy made during that time. I owned a C-Record gruppo from the era, and the shifting (Syncro 1) was utterly hopeless. STI was far more functional, in fact, 6400 derailleurs and indexed downtube shifters from that time are so good that it almost matches brifter performance. Almost.

BTW: do not - repeat do not - lock yourself into Dura-Ace 7400. The derailleurs, shifters and rear hubs/cassettes are incompatible with anything Shimano made, before or since; good luck finding replacement parts. And, the 7400 rear derailleur cannot handle a cassette cog larger than 26 teeth or so. Very short cage unit designed for a race block.

With respect to brakes, I would upgrade to the Shimano 600 dual pivot brakes from say 1991 or later. These offer far better performance than the earlier single-pivot brakes. These brakes, along with the Dura-Ace 7403 dual pivots, are as good as any brakes ever made, from any manufacturer.