The 32 windshield stanchion is mounted with two bolts.
The upper (larger) bolt can be pivoted and the lower clamps it down if the lower hole is ovalled - as many of the leaned back Deuce roadster windshields are.

Before you get into mounting the stanchions, you're gonna need the windshield frame so you can set the height between cowl eybrow (the ridge under the windshield) and underneath side of the windshield.
You'll have to allow for the "T" shaped windshield weatherstripping as well.

You definitiely want the weatherstrip, othewise rain water will go between windshield frame and eyebrow onto the dash and into your lap.

Roadsters do fairly well in moderate rain, the rain goes up and over the windshield at highway speeds.
Slowing down can get rain in your face, but no big deal.

It would be nice if the 32 stanchion would go over the holes left by the billet posts, but probably not.
Any good paint shop can re-paint the area or paint the whole cowl if necessary to hide the bodywork if holes are filled.