Getting stuck aluminum flathead heads off???

[Chris]

I thought I could get em, but man they are not budging! I am being very careful however as not to damage the heads. I got this engine a week ago, been squirting penetrating oil on each stud every day since! I have tried cranking it over with the plugs in, made some T handle pullers using spark plugs to thread into the holes, tapped and tapped on em all over...they will just not budge. Anyone else run into some suborn ones? How did you get em off without damaging anything?