Are there other areas I can check for original color?
Well, assuming the blue is a respray, it depends how thorough the paint job was. Lotus would paint the bodyshell with nothing fitted, as would most enthusiasts doing a colour change so everything looks the same. But if the base car paintwork was in reasonable condition it's likely that in some areas - the plenum chamber, door shut areas, etc, the average painter wouldn't strip to bare fibreglass but simply rub down and paint over. Areas where I've done that bodge are door shuts, underneath the front & rear valences and the return edges on bonnet/boot lids.
So if you really want to know it comes down to archaeology - you'll need to dig through the paint layers ! That's ok if the car is being painted, not so good if that wasn't in the plan.
I'm not so sure I'd be bothered unless a full respray was needed because as John said, sports cars tend to get painted more than your average run-about car and it wasn't unknown over here for these types of cars to be repainted in a more modern colour to refresh them for re-sale. Strange really - these days everyone is on about originality and painting the cars as they came out of the factory
Brian