The problem with tapping threads into it is that you use the factory style press in oil dipstick tube ever again you would be worrying about it leaking oil from the hole. Unless you barely tap threads into it.

It sounded like he wanted the option of possibly using the hole with a factory dipstick tube again in the future.

To me a piece of rod knocked into the hole would be far easier to do than dealing with tapping threads into the hole.

Using a truck pan with the rear sump means that the oil dipstick tube is mounted to the side of the oil pan rather than going into the pan rail of the block, which is why he want to plug the hole (at least for now).