So you want a vintage steel racing frame.
The ones you’re looking at are definitely racing frames. The steel used can also be a guide. Reynolds 531, Columbus SL, SLX; Tange Prestige, 1 or 2. Look for rust, ripples on top or down tubes where they join the head tube, any general signs of abuse. Make sure there aren’t any eyelets on the fork or rear dropouts (not generally used on racing frames from the 80s or 90s). Look for rust on the top tube cable guides.
Higher-quality frames will usually have two sets of water bottle bosses, a pump peg, and a chain hanger (looks like a nail on the inside of the right seat stay).
Don’t worry about geometry too much; a racing frame will have racing geometry by definition. Make sure you get the right size; don’t get too excited and jump on something that’s the wrong size because you like the color or the price or whatever. Be patient. Accept the fact that a vintage steel racing frame may not be able to accommodate larger tires. 25s will be fine, and possibly 28s.