BCRich58

I've had good luck with an older playing guide from Chuck Rainey that shows up in used book bins pretty regularly: The Complete Electric Bass Player Series. There are five volumes total.

There was a Kramer made in the late eighties that had something similar to this, it was the Kramer Ripley I think

To be honest, Sperzels are neat, although I really don't think that you need locking tuners on a bass, nor stainless steel frets for that matter, but Sperzels are excellent.

You know, that would be brilliant, honestly...

They're a real forearm workout, I can tell you that, more than I expected them to be, honestly, but a ton of fun all the same...

Amerika by Jaco Pastorius one of his easier solo pieces, but really introduces you to most of his innovative techniques, false harmonics, double stops, harmonics, etc.

I cannnot speak to price or availability in the UK, but you can usually find Mighty-Mite necks for less than the comparable Fender replacements, which are the MIM necks. I've purchased a pair of them for P-Bass projects and one has been rock solid from day one, while the other seems to need frequent adjusting, though that might be due to the flatwounds I've installed on it. Either way, I think that they're a decent neck, a bit better than comparably priced Fender necks, but not as good as the pricier Warmoth necks.

Assembled this bass during the quarantine era: Aluminati aluminum bass neck, patterned graphite fretboard, Sperzel locking tuners, stainless frets, 34" scale. Custom jazz bass style body, two passive EMG Jazz Bass pickups. I found the wooden knobs and the control panel cover via a luthier's liquidation site. Aluminati is based in North Carolina, USA, and makes aluminum necks and full instruments.

Not certain what the availability of these basses are on the used market in the EU and UK, but the Schecter Riot Eight is a really playable 8-string that can be had for under a grand here in the U.S., and might be worth your time and attention if you're interested in exploring it without a major outlay of funds:

Just stopping in to provide a quick introduction, US-based player here, forty years playing bass, ten years off and on with guitar, big fan of headless instruments of all types, small builders turning out interesting and innovative products. Proud owner of way too many US-made Peavey basses, some other interesting instruments. Saying hello to the chat room.