Found this lurking on Amazon...costs £12.99 - only one in stock (more on the way). 25 new and used available from £6.18
Amazon.co.uk: A Gun for Ringo/The Return of Ringo/Death Rides A ... The first disc of this double set contains the soundtracks for A Gun For Ringo and The Return Of Ringo, which both date from the mid 60's when Morricone was ...
www.amazon.co.uk/Ringo-Return-Death-Rides-Horse/dp/B00008WT15 - 200k - Cached - Similar pages
Only answers part of your question but it's a start.
PS In the section on this Amazon page called 'Customers who bought this item also bought' there are visual refs to the whole slew of the Spag Western album covers.
Just thought it might help you in your search.