No Power to Coil

[DreamRyder1963]

I'm working on my brother's 69 and it has no spark. Well I pulled the cap and found the points burned so I replaced them and the condenser. It still did not have spark so I checked the power coming from coil and found none, so I replaced the coil. Still did not fix it. So I checked for power going to the coil. This is where it gets strange. I checked it Thursday and it was getting 12v then I rechecked it a bit later and it had 0 v. I replaced the end going to the coil because it was barely attached and then it had 5v. I have now replaced the entire wire coming from the harness on the firewall and found that it only has 8v coming out of the firewall and 12v going in the firewall. This leads me to believe that either the fuse box or the switch is absorbing a lot of power. I checked the continuity of the switch and it seems to be fine. How likely is it that the fuse box is absorbing the voltage? The battery is also putting out 12.8 v.