One way to accurately find TDC and check the 0 on your balancer is by using a piston stop that screws into the #1 spark plug hole. Pull your #1 plug and with your thumb over the plug hole have someone rotate the engine clockwise using a socket & breaker bar on the balancer bolt to find the compression stroke. When your thumb is pushed away stop rotating. install the stop and slowly rotate the engine clockwise until it resists (piston hits the stop. On your balancer, mark the exact point that aligns with the 0 on the pointer. Now rotate the engine the opposite direction, CCW slowly until it resists. Again mark the point on the balancer that aligns with 0 on the pointer. Using a dial caliper, measure the distance between the two marks. TDC is exactly 1/2 way between the two marks.
If you want, you can back your piston stop out 1/2 turn and repeat, which will move your marks closer together, and continue that process until the distance between your two marks on the balancer is very small, increasing the accuracy of your TDC mark.