have you confirmed that your distributor is spinning around? I've seen a couple of stripped gears and broken shafts over the years.
do you have power going to the ICM?
the sockets are notorious for going bad so pull the bulbs and check inside for issues. do any of the rear lights work? if not, check the condition of the grounding wire behind the drivers side taillight.
easiest way to check ratio is to jack up one tire and rotate it around exactly twice while counting the number of times the driveshaft spins. 3 and a half is 3.55 etc. if the axle is a posi you need to jack up both tires and spin them once.