The way I see it, a reissue is a re-release of the original toy. Therefore it should be as close as possible to the original. Naturally it cannot be an exact recreation so some differences will be present but regardless, the attempt should be to make it as close as possible to the original release.
Personally, I don't agree when people call a new re-color of a vintage toy as a re-issue. These includes E-hobby exclusives like Gadep, Sunstorm, the millions of G1 Prime repaints and the TF Club Piranacon. Sorry but to me those are new repaints, not re-issues. There was never a vintage toy sporting those colors so it's a new release altogether not a re-release (reissue) of a previous toy.
To illustrate my point further, the latest 'gold' Predaking is not a reissue to me but rather repaint. The previous Takara reissue to that which was faithful to the original toy colors is the proper reissue.
Just to be clear, I am not against repainted releases of vintage molds that aim to bring something new (like Sunstorm) or show accuracy (Like Ehobby Astrotrain or Telemocha Dinobot). I very much love those repaints and I think they are awesome but I would not call them re-issues.