Yep exactly how I done it.. I used compressed air to clean the holes after tapping, Speaking of cleaning the holes out kinda off topic but it really freaked me out when I looked down in the water jackets each water jacket had a gravel size calcium rock in it!! not kidding big as a gravel in each jacket in the block!!! I used a little grabbing device to pull out the big ones some I had to break up with a long flat screwdriver and forced compressed air in there for a good hour blowing small pieces out. No wonder it has overheated on the guy who had it before me. I would say those big pieces stopped the coolant ports in the gaskets up I don't see how the coolant could flow.
