Aubuchon Hardware here (Maine) has little drawers that contain stainless 1/4-20 screws with heads like these photos that are very near the original appearance. (The originals are plated steel I believe.) I got the 3/4 inch length and shortened a couple with a hacksaw for the cover threads near the manual rewind. If too long they hit the rewind. I’d get about 12 screws to start with. Do not overtighten these as the thread in the cover halves is short and strips easily.
To replace screw number 7 I used a longer 1/4-20 screw, just plain plated. I think I turned down the head diameter to fit the spark plug cover recess. I made the bushing on a lathe from aluminum.
Good luck with your interesting project.
