Let me take a crack at this:
1962:
Ten Little Indians/County Fair becomes Back Home/Land Ahoy(making Cherry Cherry Coupe...not happen

)
1963:
Be True To Your School/In My Room becomes In My Room/Be True to your School
1964:
I Get Around/Don't Worry, Baby becomes I Get Around/All Summer Long
Don't Worry Baby gets it's own single. Becomes Don't Worry Baby/She Knows me Too Well.
When I Grow Up (To Be A Man)/She Knows Me Too Well is scratched off. No single replaces this
Dance, Dance, Dance/The Warmth Of The Sun becomes Dance, Dance, Dance/All Dressed up for School
The Man With All The Toys/Blue Christmas gets pushed to December. Becomes The Man With All The Toys/Auld Lang Syne.
1965:
Do You Wanna Dance/Please Let Me Wonder becomes Kiss me Baby/a complete version of Sandy/Sherry/whatever
Help Me Rhonda/Kiss Me Baby becomes Help me Rhonda/Do You Wanna Dance
Barbara Ann/Girl Don't Tell Me gets pushed up. Becomes Barbara Ann/Devoted to You
The Little Girl I Once Knew/There's No Other (Like My Baby) becomes The Little Girl I Once Knew/And Your Dream Comes True
1966:
Caroline, No/Summer Means New Love gets scratched in favor of a VERY bold idea. A single just with instrumentals! Let's Go Away for Awhile/Trombone Dixie
Wouldn't It Be Nice/God Only Knows gets split like AGD says but I think of the B sides different. I'd have Wouldn't it be nice b/w I Know there's an Answer and GOK b/w Pet Sounds.
Good Vibrations/Let's Go Away For A While becomes Good Vibrations/Look aka I Ran
ALTERNATE HISTORY TIME! Heroes And Villains gets released right when it's supposed to (Say November 1966) and is backed with the fabled "part 2"
1967:
Surf's Up gets released as a single and it ALSO gets the part 2 treatment (A side is the first part backing track followed by the completed track. B side is the 2nd movement.) I have it coming out January of 1967 right with the album.
One more SMiLE single. Vega-Tables b/w an abbreviated version of The Elements. This fails to sell and Brian goes back to basics.
That's all for now. I'll try and finish this up some other time.