Hi,
I have successfully refinished an old (solid) vinyl tramp. I changed the colour from mustard to black. It has held up well but requires touchups from time to time. This is easy because the product dries within minutes.
For this job you need to use an automotive vinyl dye (NOT vinyl paint). The old tramp will have to be completely stripped of "paint" and all contaminants (silicons and waxes) only then can you proceed with confidence. Stripping/cleaning is the hard part. If you take shortcuts here, they will be costly later. The dye needs a perfectly clean surface. Getting silicon and waxes removed requires special solvents such as RM900 by BASF. Any autobody place carries these kinds of solvents.
My suggestion is also to try and stick with the original colour of tramp when re-dyeing. This way, the need for touchups will be much less. You may also have to dye both the top and the bottom surfaces - perhaps not if you stick with the original coloring.
Vinyl dyes (in a spray can) are found at many automotive supply stores.
I have included links to pertinent photos of my restoration (1977 H16)
http://www.catsailor.com/bb_files/53299-MVC-132F.JPG
http://www.catsailor.com/bb_files/52248-00y1f.jpg
Dave