I'm trying to recall if I had trouble getting it off.Had to put this project on hold and was about a year ago when I took the engine apart. The pistons were stuck from the tractor sitting so long without use. I soaked them with penetrating oil a long time before getting them freed up.
Believe the head came off relatively easy. The hard part was getting the cylinder case to budge. I might should've done like you and leave the exhaust manifold on. No matter how much penetrating oil and finesse used, still broke one bolt off. I took my time too.