If it were me--and I've wanted a CrossCheck for years--I'd get some fairly stout wheels, 36 spoke, with tires at least 28mm tires (actually I'd use 32mm Panaracer Paselas, but I weigh 240) and a Sugino XD triple rank from Rivendell (
www.rivbike.com) with 46-36-26 rings and a 12-28 or 13-30 cassette. Brooks saddle, probably a B-17, LX front derailleur and XT rear, bar-end shifters (no real reason for that, except I just like them) and bars 2 to 4 cm wider than you're used to.
That's how I set up my Atlantis, and I love it.