A refinishing question

Hi paint Guru's

I've recently bought a body that has been finished ( quite well ) in what I believe to be a clear polyurethane gloss finish.

My question is this. I would love to give this bass a colour tinted gloss finish and the only product I've found that in the finish I want is a nitrocellulose laquer. If I wet-sanded the poly finish ( to prep the surface ) would a Nitro finish work over the poly one?

Thanks in advance

Darren