Yur gonna have to prove your TDC mark with a Piston stop; AND Fix the choke so it opens ALL the way and stays open. Most likely with the factory cast-iron intake, your heat cross-over passage under the intake is plugged.
But if it is not plugged, then you will have to check your cam-timing to make sure it is at least in the ballpark. You can start by rocking the crank back and forth, stopping when it hits resistance. to measure the chain-stretch.
