The other aspect, and I'm not sure how you are planning on making sure your bike measurements are going to match what you want, but different manufacturers use different sizing methods. For example, for many production bikes, I like a 56 c-c frame both seat tube and top tube. However, the Fuji I ride is their "58"cm as it is measured from the center of the bottom bracket to literally the tipy top of the seatpost clamp. It does have a 57c-c top tube, however I have had zero problems simply using an 11cm stem vs. a 12cm. Technically speaking, with obvious caveats, the top tube length and seat tube angle are two of the most important aspects of proper frame fit.
__________________
Droping the hamer since '86