[Captainfab]

When you're done drilling just blow the head out with compressed air. It is only into the water jacket and a tiny amount isn't going to hurt anything. If you're really worried about it you can put grease on the drill bit or place a magnet close to the location on the head.

The '72 and earlier trucks all came with short water pumps, so when changing to a long water pump, certain factory parts will no longer work. You will need to change your alternator wiring for the CS130/144 alternator. The power steering pump will have Metric with an O-ring fittings and the steering box in your '71 has SAE fittings. You should be able to run the newer AC compressor, but I am not familiar with just what may need to be changed. I would imagine there are several guys over in the '67-'72 message forum that have changed to the serpentine accessory drive that would have more definitive answers for you.