I have a "Schneider Xenotar 135mm F3.5" lens on my Speed Graphic. Any chance the name is a typo? How about a link? If it is the Schneider, it is a 5-element lens and should be good.
BTW: Did you look at the shots with my Real Basket Case Canon 135mm F3.5? That lens is sharp, and you should find them cheap. But not as cheap as mine...