Thanks for the comments guys. There has been some more progress, the body has been given a couple of coats of white primer ready for the colour coats. I've decided to use Tamiya Brilliant Orange as it looks close to the box art while being a little different.
The stripes and lettering on the sides are decals and I will be using them if they're still OK. The stripe on the hood isn't included but there is a stripe for the roof which I could use. The past couple of days have seen a few coats of Brilliant Orange sprayed on the body.
It looks pretty close to the colour on the box art.
Thanks. As the decals are 44 years old I thought I'd use the license plate to test what condition they were in. Sure enough it began to break up so the other decals were given a few coats of varnish to hopefully keep them intact. There were a few cracks when I put them on but apart from that they went on OK.