I know everyone says futer floor polish is the best for applling decals but would polyurethane clear wood finish work or would it melt the decals I have some of this just thought I would see if it would work.

No clues about it. Can you make some tests on scrap decals on a scrap piece of plastic? Future acts just a clear gloss coat and it's very thin so in my view it's the ideal solution to do the job!
Ciao

dont even bother with future. just use tamiya spray bottle clrea- it dries glossy. then apply ur decals after the clear is dry. after that spray flat clear over it all. it gets rid of the shine and hides the clear decal film. i use games workshop's matte finish for the flat clear. works everytime!

ah but future is a lot cheaper and yeilds better results!

"Future" is the future.