Thanks for posting that AVB - a very useful summary which I have not seen anywhere else.
By the way, believe it or not the cast iron Briggs engines are too old to be found at all commonly even here in Australia where old mowers tend to be treasured. The reason is that the Australian government levied fearsome import duties on just about everything that didn't come from Britain until the 1980s, which meant engines were nearly always British, American models assembled in Australia, or of unique local design. I can tell you, finally getting access to ordinary side valve Briggs engines after the late 1970s was a considerable improvement in many people's lives.
