Before I put a big SLR 28 on the RF (and spend that extra money on an adaptor), I would buy VInce's 28 Nikkor.
There is another 28/3.5 Nikkor (black I think) on the bay right now with a BIN of $495. I think that is high but I don't know if it's rare or somesuch. Funny thing is last week the same lens was listed with a BIN of $475, then the listing was ended early and reintroduced at $495. Someone must have told him $475 was too cheap 😀, and now its shot up out of the stratosphere to $495 😱.
But seriously, the best option is probably the CV Ultron. I don't know if the finder costs a lot. If it does, the Skopar still qualifies by your first post.