North York Marine has the OEM piece, probably around US $50 shipped. Here’s a link:
http://nymarine.ca/cowlgaskets.htm
The automotive trim that crosbyman referenced might be a workable solution at a lower cost.
Bob
1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20
“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."