Then if you have a good module (you said you tried another one) it has to be an issue with the distributor. (It is a magnetic pickup distributor right?)
Got a stock electronic distributor laying around? :D
It doesn't have to be installed or anything, just connected to the module and turned by hand works fine for testing for spark.
Also tighten up on the module to heatsink hardware if you can.
I have seen those aluminum screw sleeves not contact the backing plate of the module and not ground even with screws in them.
