I have to say at the outset - go for whatever colour you personally like. It's your machine - that sort of thing..
Second 'big thing' for me to say from the outset - I don't have photoshop, and this was done with a combo of mspaint and irfanview (altered shades, then cut n pasted the altered colour car into the original image) - my mspaint etc skills are non existant (for example I couldn't find a way to make colours look right when trying to get an idea about satin green (kinda like a green version of the satin/matt black that seems to be a big hit esp with the drifting competitors)
So bearing all that in mind, if my own car wasn't already green (so I'm going to redo it in green, so I don't have to paint the door jams etc, which are still almost like new, or the bonnet/boot underside) - anyhoo - if my car wasn't green, or I was going to a bare metal respray or whatever - I _really_ like a deep/dark purple colour. I think it looks very good on a datsun.
Obviously use this pic to get a general idea of what I mean, the 'real' colour I'm talking about would look quite a bit better in real life.

The pic was too big to save on the forum, so I uploaded to imageshack
If the image doesn't show try going to this link:
http://img824.imageshack.us/img824/486/purpledatfinal4.jpg