I have updated the web site and in the new pics you can see there is no problem with changing the spark plugs. Also, I can still fit a thermo fan in. The radiator has an extra core to keep it cool.
It is a turbo 700 transmission with a few mods (140kmh in top end of second with commodore diff).
The engine has a cam of unknown origin and mild port heads so it doesn't run out of puff through all the rev range (800rpm-6500rpm ).
Sorry about the pic size, I'm a mechanic not a computer whiz.