Nick, Perhaps these pictures below may help out in a solution to attach the regulator to your windshield. From what I could find in the various Chevy Master Parts books, the 1929-41 Book calls for a GM# 3654597 Screw - No. 8-32 x 1/2" binding head. For some reason it only lists that for 1936-38 trucks and nothing else specified for 1939-41. The later 1929-54 book shows the same thing, so it's just my guess that the screw is meant to cover the regulator attachment for all years including 1936-46, GM just didn't catch that listing error.
In checking a later parts book, the GM# 3654597 screw gets more description in the hardware listings and a pic detailing what it should look like:
Screw, sheet metal and tapping - binding head: Binding clutch No. 8-32 x 1/2" cad plated (see the pic below with the screw style drawings showing the binding head and end thread style C which is listed for this screw)
It would appear that this screw is supposed to be used without a nut, going through the tape pivot attaching pin and threading into the bracket itself. If the bracket hole is stripped out so the screw won't tighten, you could use a slightly longer No. 8-32 screw and nut or even rivet it in place as several of the vendors that offer rebuild services do. Check out picks of the rebuilt units at
Chev's of the 40's and
The Filling Station. Hope this info may prove helpful.
