If you have compression, petrol and a good spark at the correct time, the engine should run. Are you sure the timing is correct and not 180 degrees off? It is easy to have number 1 piston at top dead centre and the distributor rotor sitting at number 1 spark plug wire but the timing could still be wrong. The number 1 piston must be at top dead centre on the compression stroke, not the exhaust stroke. How do I know Easy to check because on TDC of compression stroke both valves on cylinder 1 will be closed and the rockers will be loose.

Bob

Dave, A whiff of easy start will start it for the first time if everything else is set up correctly.

Steve.

Quick update. Stripped head off again and found three inlet valves were not seating properly, even though lapped in previously. Rebuilding it now will give it another go later in the week