Another option, that can go even longer: Zinn Cycles. Lennard Zinn writes the mechanics column in VeloNews, and knows his stuff, and also builds custom bikes for really tall (and really short) people. He thinks that crankarm length should be proportional to rider's leg-length, which I'm not sure I buy (various weird physics reasons come into play here), but he makes crankarms in all the major 5-bolt patterns, up to 220mm length. So if you're interested in trying 190, as Indurain apparently used in the time trials, Zinn's your man. They come with bottom bracket, and counting that are about as expensive as the Specialties TA cranks. Here's a picture with link: