Finally finished my 1992 Trek 790 drop bar conversion this morning, just in time to take advantage of a beautiful day for a ride here in San Francisco.
Spent $50 on the bike and have probably spent another $250 on parts for it. The frame, headset, brakes (but not brake pads) and seatpost are about all that's completely original. The wheels are the stock wheels but I replaced the front axle and cones, and I swapped the rear freehub for one that can take a 10-speed cassette (along with adjusting the spacers and dish to match). Drivetrain is 10-speed 105, 50/34 crankset, Deore M591 rear derailleur ($10 from the local coop), and a SRAM 11-36 cassette (off Craigslist). I'm really happy with the wide range cassette, shifts smoothly. The hardest part was finding a stem - I tried 5 different options before settling on this one, and I cut it down a bit because it was too long to go low enough.