1989 Mitsubishi Truck engine turns over but will not start

i just replaced the head gasket on my truck the timing was set back and the engine gets compression but will not start i thought it might have been the distributor since there were no marks made for reinstallment so i tried installing the distributor cap flipped 180 degrees still didn't start and then i tried switching the plugs so plug one was on plug three on the distributor and three was on one, two on four, and four on two still nothing... any other suggestions or could i still not have the distributor right. thanks for any and all help guys