OK, just move ahead or back a short distance, and drill & tap another hole, approximately the same distance above the oil pan rail. There's nothing down there that you can get into trouble with, as long as you don't drill through into the crankcase. The thread size is 1/4" NPT (National Pipe Thread). You could also weld or braze a 1/4" pipe coupling onto the fuel pump blockoff plate, and screw the knock sensor into it. It's just a piezo-electric crystal that generates a voltage when it hears a spark knock. The computer retards the timing 3 degrees, and listens for a knock again. This procedure continues until the knock goes away, or the timing retards to approximately 10 degrees after top dead center. BTW, a noisy valve lifter will fool the knock sensor. I chased a sudden power loss at highway speed for about 3 days, until I isolated an intermittent collapsed lifter that was retarding the timing. A valve adjustment cured the problem.
Jerry
