Johnnymac, the L-bracket system is used with the butterfly-shaped bridge on the tops of carb sets from 76 on, and links the bridge to a breather box bolt, as you have done. You came up with a workaround for the earlier carb sets, but hard-mounting the bracket to the motor as you've done isn't a good idea; there should be some vibration damping in the picture. I'd suggest that you cut off the motor end of your plate, leaving only the carb bridge, and run an L-bracket to the bridge from a single breather box bolt. Where the bracket meets the bridge, drill bracket and bridge big enough for a 6 mm. screw with a piece of rubber or vinyl fuel line around it, and use rubber washers at top and bottom and in between, avoiding any metal-to-metal contact. Use light torque (~6 ftlbs) and Loctite on the fasteners between bridge and bracket. Some flex is OK, you just don't want the carbies flopping around.