I’ve just been browsing the online store of Skateboards of Choice . Based in Poole, Dorset, UK, it looks like a store with a good choice of old school gear:
They’ve got OJs and Sims wheels in stock.
Complete boards from the £120-170 range, with free delivery for orders over £50. For example, here’s a purple Z-flex Jay Adams and Jimmy Plumer complete skateboard from the 1970s