I purchased a Motobecane Grand Jubile ( silver and red for era placement) frame and fork with the stem cut off- fortunately a stub remained.

cross drilled a 5/16" hole in stem. two days of Kroil, one day each end up of steerer.

upper portion of fork in bench vise. tommybar and twist. "crack" and free.
the seller could not extract the stem.

I am still unsure how to build the frame set up. but satisfaction of the save.