Okay, here's one in the minutia column. When I was young many, many moons ago there was a tool to deburr the compensating port in a brake master cylinder from the interior of the bore after you had honed the bore. Purpose was to eliminate the sharp lip at the compensating port after honing to prevent the cups from being cut on the edge of the port. Now I can't find anything like it. Can't even find it being necessary to deburr Anyone shed any light on this?

How about a right angle dental pick? You're just looking to knock the sharp edges off.

Ever seen a oil pan bolt wrench for a model T? They exist but are pretty pointless.

Might work. The last time I THINK I saw one was when I was about 18. IIRC was a rod with a 90 degree bend at the end and a conical fluted end. But that was a lot of years ago and I don't know if my last two functioning brain cells are accurately remembering what it looked like.

Riffle file?

I use deburring tools at work and at home rebuilding transmissions. I have found them online in many shapes and sizes just Google it and there are hundreds of different shapes and sizes.

Gus