If you drain out the Oil and use something like Wheel Bearing Grease in the grooves/flutes of the Tap you will trap any chips.

The same with a Drill Bit except that you need to turn the Drill Bit slow enough with a variable speed Drill Motor not to melt the Grease.

I like the Pipe Plug idea.
I can't remember what size the Oil Pan Plug is but it might be that you can screw in the 1/4" Pipe Tap with out drilling if you are careful. Also since the Pipe Plug seals on the threads if the hole is not straight it is still going to seal if you use some Teflon Tape or other sealant.

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84 300D, 82 Volvo 244Gl Diesel