It's a 74 Barracuda and I'm assuming a 318 car so it's pretty low in the overall picture in comparison to other 1970-74 E Bodys.
With that in mind I don't think a colour change will hurt it's potential value.
Making it a more desirable colour may actually increase the potential amount of buyers.
IMPORTANT RULE:
If you want to maintain the ora of originalty it MUST be painted an original 74 colour that would have been avaiable on E Bodys.
Painting it ANYTHING else would be considered a modified car and you now narrowed the market considerbly with your own personal taste which may not appeal to everyone. Including such factory colours as Plum Crazy and Hemi Orange.

I agree strongly with the above statements that odd colours or combinations of colours such as white/green will certainly gain more attention at shows and whatnot then rows of purple and orange cars.
Nothing would look finer then a properly restored green interior in a white car.

If you truly can't stand the colour combo, and you're somewhat of a purist, then possibly consider buying another car