Question

I had a blown head gasket. I removed the old heads and repleced them with remanufactured ones. All gaskets were replaced during the work. I can not get the engine to fire. There is no compression on the cyclinders at least the gage reads 0 during cranking. I placed my finger over the spark plug hole as well and felt no compression. I pulled the valve cover off and the valves are all moving and when installed were torqued to 12ft lbs as required on hydraulic valves. There is spark, and fuel but no compression all cyclinders. I was thinking the timing chain but how would the valves move if the timing chain was bad. does'nt the timing gear turn the camshaft when the crankshaft moves? If the crankshaft is moving and the valves are moving it would stand to reason the pistons would move. But 0 compression and backfire through the manifold makes me think timing chain issues exist. This is a real head scrathcher for me. Fuel, Fire, valves operating no compression not even low.