What is the best way to clean all of old permatex from the the sealing surfaces of the engine cases before re-assembly without taking away any of the metal. I don't want to create uneven areas that could lead to leaks.

I usually spray a bit of carb cleaner on the edge of case to let the old glue soften up a bit.....I have a tri-blade scrapper that I always use to scrap the old glue out without shaving any metals off....maybe a couple on subborn areas

Then do it again with the carb cleaner and clean white rag to go over the edge, it should come right out...

j

Carb cleaner is the universal cleaner.

Also scrape it with a stright blade razor.

So stay away from brass brushes or scotch brite?

This is basically what I did when I rebuilt my motor, but it still drips some oil.

Depending on your funds, you may want to consider line boring the cases by a machinist.

Any thoughts on this out there?

I use a scotch brite disc on my air grinder after scraping all the heavy residue.