Thanks for those pictures @ikay, they'll help me determine what's what.
I don't know what I'm going doing yet regarding replacement parts. Part of me would like to source genuine original parts and put it back to original, but it will still have had a refinish then and lots going on under the scratchplate that will mean it's not worth much. I'm not doing it to sell and make money but it's nice to know you'd get back what you've spent if I had to sell one day. The other part of me says refinish it, fit suitable, retro styled but new pickups, funky colour scratchplate and headstock facing so it's a cool, useable bass.
The price, and rarity, of original parts makes restoring to original a bit of a non starter, I'd have to spend far more than it would be worth, and it might be worse to use. For example, it looks like it'll cost me £200 for set of original tuners and they'll more than likely be worse than the Schallers it's got at the moment. Although I did look on ebay and people are asking silly money for a set of these vintage Schaller M4 tuners. Likewise a pair of the Retrovibe HiGains (width dependant) would probably sound better than the original humbuckers, and the wiring is apparently quite odd in the way the controls interact with each other.
I'm leaning towards keep what's good and a pair of pickups, loom and scratchplate material would only set me back about £100ish, refinish won't cost anything. Whereas to properly restore would cost roughly £500 give or take for the parts.
But I feel bad 'ruining' what I think is a cool vintage bass.
Sorry I'm rambling now.