I'm not convinced it is a Montello. Pinarello made several others bikes in the 90's that lacked a chainstay bridge. This one is missing a few details that I'd look for in a Montello. Besides the triangles on top of the bottom bracket shell (which may or may not be there), it seems to be lacking the "flower" cutout in the lug above the bottom bracket, and there should be a small "GP" logo just in front of the seatpost binder bolt. Finally, if those seat stays were ever chrome they don't look like they are anymore.

This frame appears to match up better with the 90's Treviso on randyjawa's site: PINARELLO TREVISIO - INTRODUCTION