I'd look for an early seventies Schwinn Super Sport or Sports Tourer with straight gauge 4130 fillet brazed frame to convert. These are tough frames, came in both 24" and 26" frame sizes and had 27" wheels. I'm 6' tall with 35.5" leg length, and the 24" frame fits me perfectly. You can often pick up complete bikes for $200 or less on eBay and CL.