I read somewhere that the piston should be at TDC and the prop should be 90 degrees or horizontal,facing the 3 and 9 oclock positions.But since i hand start my conversion engines i do the magnets are at about 1:30 to 2 oclock position and the prop is at 2-8 position.I would take the hub off.Thread in a stud that matches the threads until it bottoms out.Then take it to somone with a lathe if possible and check the runout.If you dont have access to a lathe chuck it in a drill press and see if the hub is basiclly running true,no out of round effect.