Weird Ignition Problem

[techsan]

A friend of mine just swapped short blocks, and everything was running fine. We changed the plugs, wires, etc. and everything went to hell quick. We initially had the firing order off, switched 5 and 6, and when we changed it back the car didnt fire. We have no spark when the car is turning over; however, once the key is turned from the start to on position the coil fires one good spark. So the car does not fire on crankup, but does just after you stop trying to crank it. We have checked the MSD box, Ignition switch, distributor, and control module. We also tested the fire by removing the distributor and spinning it by hand with the key in the on position, and the coil fires just fine. We are totally stumped and out of ideas. Any help would be greatly appreciated.