Other thoughts
Confucian Missionary 12, the one in Barcelona, has already partially moved this turn, so don't plan to move him until T277, so that he doesn't die to Mehmed's units.
Bribing Toku out of war and back into war should prevent Toku from vassalizing Mehmed.
Based on having tracked AI modifiers attitude in the past, as long as Scores remain constant relative to each other, then Isabella will be Friendly with us at +12. She is +9 with us and we can get +3 from Fair and forthright trading.
So, if Music is enough to get her +3 (be sure to gift it, not asking her for Gold in exchange for it, to be certain), then she'll be at Friendly. At that point, you are able to get things that we've waited for from her for a while:
a) The ability to request her to switch Religions
AND
b) The ability to get her World Map
I'd say use Divine Right in trade for those things (Buddhism, plus her World Map, plus her remaining Gold), should Music be a sufficient Gift to push her up to +12 with us. If Music isn't enough, gift her Divine Right and then pick another tech (Guilds? She doesn't have a Horse Resource... not Paper unless you're also giving that to Zara, and if you are giving it to Zara, give it to Zara first).