Only today I became aware of this article in the Financial Times Magazine on work being done at St Catherine's at Mt Sinai. Not only is it worth the read, but it has a beautifully worked photo of a leaf of a palimpsest of Paul (1 Corinthians, to be exact). I had not seen this one before, and for the moment I assume it is 0289, which is listed as a palimpsest, is supposed to contain 1 Cor 3, and its overwriting agrees (I think) with the image of ΜΓ 99 I have in the New Findings catalogue.
This is the image as it appears on the FT website (© St Catherine's Monastery), rotated 90 degrees:
The date given in the Liste is VII/VIII and this is what made me doubt my identification. Given the closeness in lettering to say Codex Bezae or Alexandrinus, I would be comfortable with a fifth century date. OK, there is an enlarged initial, something (re)appearing in the fifth century, but the upsilon still looks earlier than some later versions of this Biblical Majuscule. The overall lettering is nice and square.
People wiser than me are welcome to correct both my identification of the image with 0289 and/or my feeble attempt at redating.