Thanks for chiming in Jerry.

You're right about the backlash, it lines up square on if I turn the crank the other way.

I can't check the keyway as the front nut is bigger than any sockets I've currently got access to. The engine is out on my garage floor and stripped for cleaning/painting. Just bolting parts back on it now.
Both exh and inlet valves are closed, the dowel on the crank is at 12 o'clock which all makes sense.

However the timing marks on the case (16,12,8, T) are clocked over and the pulley notch lines up with the T. I'm happy with that.

I figure if I was one turn of the fuel pump out, then either inlet, exhaust or both valves would be slightly open.

Cheers
Dougal