surfboard( old 60's ) longboard.....?

I wish you included a picture. It is probably a board built on a polyurethane foam blank with a wooden stringer or stringers. If the paint is regular oil based paint, you can actually sand it of with a light grit wet/dry sandpaper, and then it may be possible to re-do or touch up the gloss coat of resin. However, usually when those old beaters got covered with a coat of opaque paint, it was because they had lots of "bruises" water stained dings that discolored to a dark brown. So, it make take someone who is a fair hand at glass and resin work to really restore it.

If the paint is a 'poly-poxy" based marine paint, it will be harder to get it off, but not impossible.

My great old Weber Feather (C) 1969 was like that when I first got it, but I actually paid a great ding man to bring it back to life. If you take your time, and do it properly, the board could be worth a good deal of money, and will certainly be a great collector's item to hand on your wall.