In most cases, the Santana is very different from it's Solihull cousins which as you know can make locating parts difficult. If there were someone who could publish a complete parts list, than this would benefit all the Santana owners.
Have worked on a number of Santana's and while many of the interior, suspension, differential, and body parts look similar, they are different starting in the 1970s.
Consumable parts like brake and clutch parts are shared with the British Land Rover, but the year of manufacture can be completely different, so what I think you really need is a cross reference from the Land Rover part number to the Santana make model and year. While this is no easy task, it could be started and become "a living document" that Santana owners can fill out over time as they discover the answers.
Hope this helps.