What makes you say that?Looks like he's got far lower compression than the original head from memory
The glass looks to be getting on for 10mm or so from the top of the piston. When you see it disassembled, there is a clear void milled out. The spark electrode enters from the side and is sparking to a post between the cylinder and inlet valve. The post is around 8mm long by the looks of it.What makes you say that?
I seem to remember them as flat with the sparkplug above the piston. His looks about the same. I did think that TDC looked low. Perhaps a shorter conrod?
The side valve "wastes" a lot of space. Never seen it in situ like that.