340 Static Compression Numbers and Test Procedure

Ok so here is an update. I thought I would start with the basics first and not make any assumptions with the set up. So I thought I would start with the distributor set up. What I found has confused me. There is a painted line on the harmonic balancer that I have been using and appears to correspond to TDC. However the harmonic balancer factory scribed mark line does not appear to line up with TDC? Are the HB keyed so that the factory scribed line/mark are always TDC? Why would the factory mark be off?