I didn't know about that resource for palettes, so thanks for the link i'll have to check that out.
Also while i have some small knowlege on some of the limitations of older system to have a vague idea of what to aim for to have retro a retro ish style, i can only say RESPECT as of your technical knowlege here ^^ and i can only add a O_o face for the courrage you had making something aiming for spectrum specs considering the insane limitations this must have.
No worries about your info dump though it was interesting :)