Well having given the old bus a good going over with a ruler, I found out it's actually underscale. It's actually about 1/36, which is noticeably small when put up against 1/32 cars. However I'm still going to do it because as a scenic item it should still look good if placed at the back of a layout. Plus I found a Jaguar Mk1 (?) plastic body which is exactly the right scale to fit. I'll eventually make a couple of copies of the Jag, so I can hopefully put one inside the bus on the lower deck, and have the other two as slot cars.
Here it is, still looking a bit rough at the moment. I'm hoping it will end up looking toy-like.

It'll hopefully end up something like this. It should look good with vintage adverts on the sides...
