Don't know much about clear coat (speak to an auto sprayer) but a bit of wet and dry on the gelcoat works wonders (and is what I do with mine). If the stock will allow it just work up to 1200+ (2000) grit and it comes up shiny and slick.
i do auto spray painting allmost everyday , ive done a few stocks for myself . its pretty easy - just wet sand it starting from 1500 or 1800 . clear coat with acrylic clear coat or better still 2k clear , then let breath out for a few days if you have the time / then re-WET sand using 2500 or 3000 paper . buff - comes up excellent - depends what finish you are after. wear a mask when painting . you,ll live longer to shoot . lol
Re furbish the old surface first and best option
2K clear will also do the job just remember you are applying a clear finish over gel coat
If the surfaces are not kept absolutely clean the over coat may fail.
RB