Plus, you wrote "I can use my existing lensboard ..." If you have in mind to use one board for two lenses, don't. It is much better to dedicate a board to each lens (including shutter) you want to use.
Also, if y'r 135 Optar was made by Wollensak it will be in a Graphex shutter made in Rochester by Wollensak. These shutters don't conform to the Compur/Copal/Prontor sizes so you can't mount a lens in a Copal #0 (that is what you're getting, isn't it) on a board cut for one. If y'r 135 Optar was made by Rodenstock ("made in Germany"), I'm not sure which shutter it will be in, might be a #0.