The trick to riding 1200k in 90 hours or less is, as said above, being able to ride consecutive 400ks. In an SR series, the first time one gets a taste of that is riding that 400k with a 200k after a very few hours' sleep. It becomes quickly apparent that one has to be able to ride fast at a low effort level to be able to recover well enough to do that. And PBP is not flat, not at all. That doesn't take great talent as much as it takes great conditioning and an ability to suffer while still riding well. Lay down a huge aerobic base this winter, then attempt an SR series each summer. Probably won't be able to finish one this coming summer, but try. Main thing is to accumulate a lot of miles/year by doing a lot of long rides in hilly terrain. You can get in more miles by keeping the effort down.
A great bike would be any 9 or 10 speed carbon bike with an Ultegra triple, 53-39-26 on the front and anything between a 12-25 and 11-30 on the back, depending on your strength. Trek 5200 is a good choice, available for between $600 and $900. You'd have to figure on new rings and cassette.
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