I think the seller has made an error. A 44cm frame with a horizontal top tube would not accommodate 26"/650 wheels. I believe this frame requires 24" wheels. If the wheels were marked 600, that equates to 24".
The question is, which 24/600 bead seat diameter? A "600" marking with no suffix would imply 540 BSD. Given the Japanese origin of the frame, the rims are probably Araya and they typically marked the suffix. However, to be sure, you should get the seller to take rim measurements and the previously suggested frame measurements.
Tange 900 typically indicates a mid-1980s model of upper entry level to lower mid-range quality. It was a seamed, butted, CrMO tubeset. In this case the presence of stamped dropouts indicates it is almost certainly Tange 900 only in the main triangle, with hi-tensile stays and forks. If so, I would classify it as upper entry level for the period. Normally, I wouldn't offer anywhere near that amount for a frame of this level, but the very small size does command a premium.
Edit: D'oh! Screwed about doing the conversion in my head! 44cm could handle 26" wheels. I was thinking 44cm =13", not 16"! Still, if the matching wheels are 600, that's 24"
Last edited by T-Mar; 04-06-13 at 10:15 AM.