Hi there,

Welcome to the forums!

Lesson nr 1: Drive side pics please (so we can see the drivetrain )

That's a neat bike! Is the brand a Slovenian one? That would be very interesting, especially if you know who made the frame.

The wheels appear to be a normal size, 28 inch. If it were a kids bike the wheels could be 26 or even 24 inch. For tubulars, it is normal that their size is called 27 for a 28 inch wheel. You need to stretch the tubular before actually glueing them on the rim. Best is to put them on the rim for a couple of days without glue (no riding them yet!), then they will stretch a little so mounting after glueing will be easier.