John,
Many thanks for those pics, and what a great head that is, Half a dozen deep fins rooted directly to the top of the combustion chamber and able to conduct maximum heat away from the hottest part of the head . Nice to see minimum interruption of the fins to accommodate the plug and studs and the fin spacing looks right to promote high speed air flow, again to extract heat efficiently ! The ratio of fin area to combustion chamber is very high and that always helps to keep things cool !
10 out of 10 I would think , well done Don !
Cheers , Trevor