I did an electric starter conversion on a ’56 Johnson RD-18. If it helps you visualize any, here’s a few shots of my starter/flywheel arrangement during the assembly process. Yours should look fairly similar. Sounds like you have an Evinrude starter bracket without the cowl pin but it should work. The correct Johnson starter bracket would be part #376885. The ring gear mounts on the underside of the flywheel.
Bob
1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1955 Johnson QD-16
1957 Evinrude Fastwin 18
1957 Evinrude 3022
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20
1982 Evinrude 25hp
“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."
