New oil pressure switch doesn’t fit...318 LA

What about the rest of the pipe threads in the block, did you chase them too?

There is no way that I would trust that. Not only due to the potential for leaks, but also the very real possibility that it could, with temperature and vibration, blow the sender right out..... on the highway or at the top end of the track and empty the contents of your oil pan in a hurry, oil under the back tires, engine run dry, you get the picture.

You have two options that I can see. Number one, stuff something down in the hole to plug it and drill and tap to the next PIPE size, then use an adapter bushing, or figure out exactly what thread you cut, make sure the thread is in decent shape and use a straight thread fitting with an o ring or crush gasket to adapt it to pipe thread.

FYI, i don't believe that your pipe dope will harden as you expect. It is meant to remain soft and pliable.