[Hozer 88GTConv]

No compression at all means a bad valve setup to me. Either poor adjustment or a collapsed lifter.
If you had low compression, I'd say rings. But NO compression, got to be a poor valve seat/adjustment at least. The stuff in the cylinder is just fuel and a little oil.

I would absolutely verify the valve adjustments by taking the intake manifold off and watching the lifters. Make sure you prime the oil pump so the lifters are pumped up and you set the valves right.
I just did this three times a month ago. I hand cranked the motor over and went down the firing order. Then, cranked it over and made sure it all made sense.