I have to say that I find the existing releases of The Rocketeer and Willow both very satisfying.
Particularly The Rocketeer is one of my all time favorite James Horner scores, but I don't think it particularly yearns for expansion.
In any case, over the years many of my one-time holy grails have been released. Among the film scores I have yearned for to be released or released in a more comprehensive form a one time that have now been released:
Lawman (Jerry Fielding)
Alien (Jerry Goldsmith)
Logan's Run (Jerry Goldsmith)
Scorpio (Jerry Fielding)
Gremlins (Jerry Goldsmith)
Monsignor (John Williams)
There are a quite a few more that once were holy grails but are (or at least have been) available, even such outlandish ludicrous wishes such as The Omega Man.
Interestingly, once in a while there was an expanded all up to date release I had to pick up only to find out that the expansion was not really necessary. I'm thinking of Hook in particular, where I always wanted to have an expanded CD (including the end title sequence) only to find out how cohesive a listening experience John Williams' orignal album was. Mind you, I am not parting with my LaLaLand Hook, I'm sure glad it's there, and hey, it's got a booklet and liner notes, and more music, so I like it quite a bit, but the original release was not lacking in comparison and seems like a better rounded listening experience.
There are some scores I have that I would not mind to see re-released one day in a more expanded and remastered form one day, like Psycho II and Dracula (Williams.. one of my favorite Williams scores)... but at least I do have them (on both vinyl and CD).
On the other hand, whenever I thought I did not have any grails anymore, somebody released something that was a grail of mine, sometimes a grail for so long that I have already forgotten all about it.

One of those ancient, all but forgotten grails of mine would be the soundtrack for Five Card Stud by Maurice Jarre. Now that one would knock me over with a feather. Also Duel at Diablo by Neil Hefti comes to mind. (I know it's been released as part of a collection.) A complete Damnation Alley would be neat, perhaps the most significant Goldsmith sci-fi score without a proper release. And speaking of Goldsmith, boy, would I be game for a re-recording of The Mephisto Walz, a true Goldsmith gem, but the original recording sounds terribly dated.