Hi Graham
You should get it somewhere near and then use a strobe once you have it turning over. I guess at a push you could remove the plugs and spin it over on the starter and still get strobe light pulses which may work. Personally I would get it started and assuming you have the carbs setup somewhere near and then use the strobe light at idle.
Peter
That's not a bad idea at all. Removing the plugs and spinning it over on the starter should allow me to use a strobe to set the timing at (nominal) idle. I guess I'd need a pretty heavy duty switch to handle the current. And what sort of rpm would a WOSP style starter motor be able to generate, I wonder? The engine still only has assembly lube on the bearing surfaces, so it will need filling with oil before trying any starter motor action.