Do you think Ob-La Di... or Yer Blues could actually hit #1 as singles? It would be hard to name any track off the White Album that would (maybe BITUSSR or WMGGW). I'd rather Paul and John save them for their solo albums, where they can do the least damage. Of course, all of this is perfectly well and good in hindsight...
Harrison's quality in contributions goes up and down over the course of all the post Help! albums. I'd cut Piggies and Savoy Truffle if I could get "Not Guilty" and While My Guitar Gently Weeps on any White Album. When he's good, he's good...when he's bad, he's singing about chocolates.
It is really hard to reedit track listings without knowing the songs very, very well and taking a lot of time to do it. It would probably also help to actually be a Beatle in 1968.
Obladi Oblada was released as a single in a few countries, and it did pretty well. The song was one of the more popular tracks off the album at the time apparently. It wasn't a single in Britain, but where it was, it did well. So, maybe not #1 but it'll be up there in the charts in my estimation. Yer Blues is obviously more questionable, but the three options are single, on the album, or an early Plastic Ono Band Release.