Well, that's a bit of fun, isn't it; looking at the instrument the options are to either: (a) view it as the fun mongrel it is, or (b) take it on as a project which needs work and money spending on it to do a restoration.
But restoring would be non-trivial.
Unfortunately (though I do have a set), putting wavy Grovers back on is not a simple job, as the peg holes have been widened to fit the Schallers; reverting would require filling the holes and re-drilling original-sized ones, after which the repair would be visible.
Many 4000's left the factory with the Bass (neck) pickup routing already there, so the 4000-4001 conversion was a simple job; unfortunately this one wasn't one of those and its extra pickup is in the wrong place.
There's been a lot of wood taken out of the body and at the end of the set-neck and that's weakened the structure; Rics are prone to neck-lift (where the pull of the strings starts to lift the neck forwards); thought I'm not sure about how the set-neck models are affected, this one needs the routing filled in with the correct wood (maple) to put it right.
There's the tail-lift issue which isn't too difficult to resolve: just replace the tailpiece or go for @briansbrew's excellent fix!
It's a shame about the butchered pickguard; replacement 4000 ones aren't so common.
I'd be looking to do the restore, but it could be a money-pit and the end result would still be a not so great one.
Of the 8 Rics I have, only one was more than this one's asking price and my most recent one was an '88 4001 project which was missing some parts but not needing any structural work (coincidentally, one of its pickups was acquired from @briansbrew some years ago).
There's a 4000-sized gap in my Ric collection, but making the numbers add up for a restoration on this one would require @Clarky taking too much of a hit.