Shame your not in the U.K, as I have plenty of the original BMC Surf Blue paint in stock, infact apart from Island Blue I have every colour in stock for the Coopers, I could try to send you a small bottle of it and see if it gets through the postal system ....
For the Powder blue seats, I used Windsor & Newton Powder blue acrylic artists paint mixed with Testors acrylic thinners so it could be airbrushed, here's a Tamiya Cooper S I built last year .....