I assume it is(was) a 150. The original red is Lechler code 8073. Are you spraying all of the scooter or just part? Paint fades and any part only spraying will probably stand out like a sore thumb, especially red. If you are only spraying part take a piece of the scooter and get it colour matched at a specialist. Don' t know where you live but I have used these guys near Bolton. Very good.
If it is an original Italian GP200, then 8073 isn't the right colour - This is a mistake that has been carried forward and was only recently understood. The correct colour is much more Martian. Take a look on the GP Anoraks page.
Halfords do a mix and match can blend any colour for £16 i was well happy they also do a touch up pen all while you wait ideal for small bits worth a look for ease and money .