it originally came with a 700c fork, so that's probably what you want. The measurement you want to replicate is the axle-crown (AC), preferably of the original fork.

You may not have the longest reach brake, I'm pretty sure these came with the mid-reach version. Could be wrong, of course.

The original fork had eyelets. I don't know if you can get one of those though.

I'm moving this from framebuilders to C&V so you can get better help.