I have two coil packs. One was with the car. The other was off of a mustang(not that it matters). As for the DIS and cam synchro, what can be done?
Lots of testing and diagnostics. Process of elimination. Having a DVOM or a graphing multimeter with an EVTM helps a lot.
Assuming you have good compression on a freshly rebuilt engine, timing chain was installed correctly, and CMP is within manufacturers range.
CMP - Ive had "bad ones" that threw a check engine light but worked perfectly fine. Typically the engine will fire, but it may not with a bad one. Try un-plugging it and see if it starts.
Check for spark - not necessarily pulling the engine plug, but with a spare wire / plug.
Check coil pack, power / ground, check for signal from PCM, check resistance/continuity in coil pairs.
DIs module - may be able to bench test at AUtozone, etc, check for signals, etc ..
Really hard to diagnose a no start condition over the internet. Common thought is that you need air/spark/fuel, but there are two more, compresion and timing. In this case, I am leaning towards the spark/timing its the most likely - check for spark, if no spark, trace it back through the components. The voltage drop with the coil pack plugged in - thats where id start looking into electrical wiring / components, its not exactly normal to do what youve described.