>>9923309>Is it difficult to take his head off?It's pretty easy. I was a beginner earlier this year and after head swapping several dolls I'm pretty confident now. You want to heat the head first to soften the plastic, either with a hair dryer or hot water. My preferred method is boiling a little water and pouring it into a mug, then wrapping the head in a ziplock and dunking it for 2-3 minutes, so the water can't get inside of it or ruin the hair; if he's the same structure as Dumbledore, his neck peg will look something like this, and the most dangerous part are the "arms" of the peg which can catch and tear the neck. Since Sirius has molded hair you can probably strip his shirt and dunk him right in to make sure the water warms him up all the way through, but keep in mind some water will leak inside and could burn you when you pull it off. Let him dry out really well before putting his head on another body so you don't have trapped moisture, because vinyl can mold.
If you use the hair dryer method, don't make it so hot that you burn yourself or start warping the doll head. Start at lower temps and work your way up if it doesn't get soft enough. Focus on the base of the neck.
You can also search up "ken doll head swaps" on youtube and there are lots of videos of people removing the various types of heads. Even within the same line there can be releases of dolls that have different types of neck pegs, so since I don't have a Sirius myself I can't tell you exactly what he has in there.
Getting it to fit on one of the other body types might be the trickier part, since the neck pegs are completely different. Best of luck!