billy b,
a supercat? never heard of that one.
Have you ever heard of 'power cat' boats? they were in bellflower before movong to texas in 62 or somewhere around there.
i don't have a source for the cowlings but there's a cool couple of web sites that might be able to help you out, both dealing with power cats.
the first one is,
http://www.powercatboat.com/.
its mostly a site dedicated to the history of powercats, done by the son of the guy that owned them. they do have a want add page that you could post an add on, but the other site...
http://groups.yahoo.com/group/PowerCatBoat/messages
is a dissucision site and i'm sure you could find what you need by posting over there. those guys are heavy duty outboard guys, a few of them anyway, and are really into the vintage stuff.
i'm not 100%, but i think a 60-1 merc cowling was all white, no black yet. there's tons of pics from those years on the first site. there's also some great pics of a 14 powercat with twin 80s, all white, from 1961 that ran just over 80 with that set up.
those things hauled ass for the times.
got some pics of your cat?