Welcome to the forum!
Firstly, your best bet for a tune is MAP. They have lots of experiencing in tuning the S550.
Secondly, if you're on Facebook, come and join us at https://www.facebook.com/groups/SimplyMustangsUK
The guys at Modurstang are great and they actually offer a replacement oil cooler system (as do GT101, but they're based in Essex). Finger's crossed your engine is OK.
Two other highly recommended specialists are
Motorsport and Performance (Yorkshire)
I don't recall seeing it posted here, but ThePill kindly posted it over on Mustang7g. Norm was active and respected on a number of Mustang forums. A little late, but my condolences to his family and friends.
Brittany Blue debuted for the '67MY........and that's a '65 or '66 coupe.
However, Ford did have several light blue metallics for those model years which were all similar to BB
This is a good reference site with links to photos of the various colors :)...