Dingdingding! We have a winner!

Any engine shop should be able to hot dip/ bake/ soda blast/ magic keebler elf clean it or whatever magical method they posses.

__________________
$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment

Well qualifying that statement with "should" makes all the difference. A lot of shops in California won't put it in their tank, believe me I've tried. Plus they charge you every time they run it through. I haven't tried the heating it up technique.
At $45 a shot it adds up. Sometimes that stuff is thick.