Originally Posted by
Ingleside
If you can find older 8-speed Dura Ace or Ultegra shifter they would work with your set up.
You can also use Sora 8 speed shifter from a few years ago which work pretty good or even some Shimano 2200 level shifters, but they kind of lack in the performance department.
You actually cannot use 8 speed Dura Ace with a 105 rear derailleur. Dura Ace 8 speed rear shifters and rear derailleurs only work with each other. The front derailleur and shifter will work with any other shimano exept for Dura Ace 7900 though.