Neil,
I like his ports, not the same as ours but a good setup also. Ours are configured with the butterfly close to the inside. It really seems to help the idle. Our PSRU has an adjustable mesh and everything will idle down to 1100 engine RPM no problem. (while swinging a prop on the dyno.) I plan on a proper slide throttle, (hard slide with bearings), to go even further. I'm on Paul Lamar's newsletter and while there is a lot of dross, there is some good info there. Recently there was a post from someone that had info on the Merc. C111. I got several items of information from the drawings and pictures, also 1 patent. They put the throttle butterflies exactly where we do.
Bill