Jeff,
Where are you mounting the DIS in your buggy? When I moved mine from the crossover tube to my Command and Control box (sometimes referred to as a can of worms) behind the passenger seat, I made a grounding plane out of 1/8" aluminum plate that covered the bottom of the box but stood off from the floor by 1/2".
To this plate I attached the PCM, the relays, fuse block and the DIS. This plate was thick enough to drill and tap holes for everything and since it itself was grounded to the negative side of the battery by a #6 stranded wire, it was perfect for supplying the grounding AND more importantly, the heat soaking that the DIS module needs so desperately.
I smeared a thin layer of dielectric grease on the back of the DIS before I mounted it down permanently to aid in the heat transfer and to keep water from between the two surfaces.
Pin 7 of the DIS is internal ground so you could check continuity with a VOM between that pin and the screw holes to check, maybe.
If you extend the wires of the cranshaft position sensor or the DIS, don't forget that those wires must still be shielded and bonded to ground also. Since I made a whole new wiring harness for The Other Woman, when it came to those wires, I added a bare drain wire that goes to gnd, wrapped them all up with 2" strips of aluminum foil followed by half-lapped layers of 3m 88T vinyl tape (the best vinyl tape by far). While those shielded wires are still in the main bundle with the other 42 wires, they are in a separate shielded sub-bundle.
EDIT: I just went out to the shop and checked one with a VOM, and like Timbo says, the two bottom screw holes are grounding points, common to pin 7.
Tom
