Cajun,
If you are running a data acquistion system be carefull. If you are, use only one ground point for everthing. I recommend using one wire from each head, one from the ignition, one from everything else to a 1/4-20 stud. If you have more than one ground point you introduce what are called ground loops. The ignition will emit RFI which will radiate to the ground loops which will then mess the data acquistion up. This not a small point, it is very important. Do not use the frame as a return path when you use a data acquistion. We do this on Top Fuel cars and we did it on our lakester and the Racepak data is perfect.
Sorry for being a no-it-all, but it comes with being an engineer.
POPS