Just read your first post again. I see you want to stay twin shock. With a B12 arm, you'll need top hats to take the swinging arm spindle diameter down, (assuming 750 & 1100 frames are same width at 'arm mounting point). Otherwise 'arm may need mods. Get weld on lower shock mounts from Lucky 7, find a nice man who can weld, and away you go. As said before, a std. Kat/1100ET arm will fit with no mods, take a 160 no bother, or a 180 with a bit 'massaging'. Only going by my experience, as a 180 rubs against the stiffening webs on the inside of the arm.