Did you try moving / adjusting dizzy to different positions while starting ? Maybe timing is pretty far off . Lining up the oil pump has to been done accurately . That 11:25 o’clock position can be tricky to eyeball and it wouldn’t take much to be a tooth off.
Double and triple check firing order.
Whats it doing when you try and start ? Spitting , coughing , nothing ? Try squirting starter fluid in while cranking ?