Here are some links that come up when using the search bar.
http://www.y-blocksforever.com/forums/Topic32479-3-1.aspx
http://www.y-blocksforever.com/forums/Topic2562-3-1.aspx
I’ll add that a small pipe wrench around the base of the distributor can sometimes help to break it loose but this is best done after the aforementioned soaking with penetrant has been performed. Work the wrench such that you are trying to move the distributor in both directions until it does break loose.
I do come across quite a few stuck distributors in core engines but because the engines are typically on an engine stand or where I can flip them over, I have the luxury of soaking the distributors from both the top and bottom before attempting to put some serious effort into removing the distributors.