BTW, just to clarify some final points; the fence has 15mm thick PEHD-500 plastic attached to each side and the zero clearance insert (s) I made from hickory.
I also discoverd quite late on that the saw has a genuine riving knife that moves up and down with the blade, not just a splitter that only tilts. This doesn't tie in with what I've heard was the norm on such an early model but maybe it was something special done for export ? According to the machine number the saw's a 1963 model.
A short resurrection of this thread to show what I've recently done with the crown guard and riving knife.
The original guard obviously had no extraction so after looking into making one myself I instead bit the bullet and ordered a Sharkguard and replacement stainless steel riving knife from The US. I had one on a previous saw and they're really excellent, although not cheap :shock:
The top of the replacement knife is lower than the blade, with the obvious advantages, and the guard has a quick release mechanism that allows it to be very easily removed. And the extraction from the 4" outlet is fantastic !