Thanks guys. There seem to be two different clamps, one with a single bolt and the other with two. Either way the clamp is probably too deep.....
And yes I bought a funky Cyclecat yoke. A work of art it is too but for the cost it should be. I could have gone with boring out my SL yokes but wasn't comfortable with the idea having seen what lousy metal they're made from. Seems to be fairly common in the States but the idea of them giving out while hard on the brakes at the end of, say, Snettertons main straight puts me off.
I got a good deal on the SBK forks though and should recoup more than their cost when I sell my SS forks. I guess I'll have to abuse the credit card again and splash out for the matching CC bars.... Time to convince the wife they're service items....