I think the value has pretty much been covered (£1000 - £1500). As to the bass you've described;
[font="helvetica, arial, sans-serif"][color="#282828"]In 88 there was no CS as such it was a case of customer options were accommodated at the factory and that included 12/24th fret inlays saying 'Custom made for...'. The body wood bubinga is standard and the earlier basses often had very nice figuring on the woods (more marked in the early SSII basses but often on Thumbs; oddly enough the 90's was a better decade for the figuring of maple on SSI basses). The LEDs would have been an extra cost option (if they are original)[/color][/font][color=#282828][font=helvetica, arial, sans-serif], Pups could be one of at least 5 manufacturers and Bartolini is one of them. The slimmer neck profile is a feature of these earlier basses and many seek out early basses due to this, one thing often overlooked is that the edge of the fingerboard radius is generally very smooth and makes these a pleasure to play. [/font][/color]
[color=#282828][font=helvetica, arial, sans-serif]There will be folks who want green LEDs and Bartolini pups and may well pay a premium as a result. However, despite the new price being mahoosive, you'd only get £2k if you were lucky to snag a specific buyer looking for these options.[/font][/color]