Sorry, I genuinely don't see this one. And you know how much of a huge Deidara fan I am. Hanzo said Mifune is so fast that he makes ninjutsu effectiveless, Deidara would only have enough time to throw out his smaller clay bombs to buy time for the bigger ones (and the dragon which admittedly would be game over for Mifune) but Mifune has such pinpoint accuracy, he can easily cut every minor bomb in half like he did in Aesthetics of an Artist, and even then Deidara was an edo.
This fight goes either one of 2 ways and is over very quickly you know? Either Mifune cuts the normal bombs and is on Deidara in seconds (which anyway means death for Deidara, this IS mifune) or Deidara somehow creates something big enough in his few seconds and disorientates Mifune, making for a normal fight which with bigger jutsu and more distance, Deidara can win.
Mifune wins 7/10 times IMO.