I would not use monokote on a plastic (ABS ) cowl. The heat needed for the monokote will distort (at a minimum ) the cowl and possibly actually melt it.

Lusterkote is SUPPOSED to be a match for monokote. Personally I can not stand the stuff - it "spits", lays poorly, and the color match may be close (MOST of the time ) but you have better odds of winning the lottery than getting an exact match.

You best bet for a paint is to have some made up and color matched.

Many people use automotive paint. It is very good, but can be pricey.

You could also see if you can find a color match in something like Krylon (you will need to clear coat it ), or one of the automotive touchup spray cans. Rustoleum may also work, but from what I have read, it may or may not be fuel proof so plan on clear coating it.

I use latex and then clear coat it. I have had no problems AS LONG AS THE LATEX HAS CURED PRIOR TO CLEAR COATING. Curing takes about 7 - 10 days.