This can frustrating but you really need to verify TDC before you can set the timing. You can use a piston stop that screws into the sparkplug hole. Remove all the sparkplugs. This makes it easier to turn the motor over by hand. To be safe pull valve cover and loosen rockers on #1 or shaft assy. if non adjustable rockers. The reason for this is that in some cases the valve could contact the piston stop as it is opening. Screw piston stop in #1 sparkplug hole. Turn motor over by hand GENTLY until piston bumps against the stop. Put a mark on the balancer that lines up with zero on the timing cover. Now GENTLY reverse direction until piston contacts the stop. Again place a mark on the balancer at the zero mark on the timing cover. REMOVE THE PISTON STOP NOW. You don't want to accidentally leave it in and crank the motor over with the starter. Last step is to measure the half way point between the marks placed on the balancer. This is TDC.