FWIW I've got a set of Williams I ordered last year, bolted to an 838 head on a 55 block on a stand in my shop for a future project. Using an Offenhauser 216 dual carb intake it bolted right up using a set of stock clamps. I did do a little hand filing on the center exaust extensions back sides to remove a little angularity in the clamp, but it was just a few minutes work. The faces were lovely, machined flat and parallel. I liked 'em.
I vaguely remember hearing somewhere that the Offy was their intended set up, but cannot confirm.
