The restoration looks great!! I completed a full resto on the same year and model a couple of years ago. You should be able to remove the pin stripe glue with Acetone. It won't hurt the gel-coat. Also, if buffing will not bring the colour back like you want it, don't be afraid to wet sand the boat. It's lots of work, but the results are awesome.
Good luck with the project.
1990 Prostar 190, 351 Indmar SO, bought as an empty shell and rebuilt over the winter (04/05). Sold in May 2009
New boat - 1993 Prostar 205. Bought in better shape than the 190 was but still needed some work.