Just find someone with a good caustic soda hot tank. Mine is 4x8 and ive dipped housings and they come out near like a new part in three days. Probably be easier and cheaper then your time and gallons of evap.
That's hard to find in the northeast thanks to the EPA, there used to be a place with a big dip tank ... can't remember it nationwide chain ... that I had the frame to my 56 chevy dipped in back in the 80's
