The easiest way to fine TDC of #1 on an assembled engine is this. Remove the coil wire. Remove #1 spark plug. Use your finger to cover the #1 spark plug hole and have someone to bump the engine over. The compression of the engine will push your finger away when #1 is on the compression stroke. It should be close to TDC. Line up the timing tab with the mark on the harmonic balancer. #1 is at TDC.