Maybe your are finished with this project. But here is what I did on my 1979 Tartan 37.
Epifanes Non-skid (yellow shade), paints on heavy, like a primer almost. Came out beautiful. Two coats were needed to make it looks professional.
For the white top coat, I used one-part Pettit EZPozy. It rolls out very thin. It appears watery. It even says, this product is thin and needs to go on in light coats. I used a foam 6-inch roller. It came out really good. Two coats. Feels like gelcoat: shiny and nice to touch.
I was trying to remember what I did first. I think I did the white first and then taped. And the non-skid went on second. When you peel off the tape the white lines look perfect. Get the best (most expensive) delicate tape you can buy.
good luck.