Need advice for 3.75 figures.

I'm not sure of the peg holes and such but generally heating and popping will do the trick. Just give it a blast with a hairdryer for about 1 minute or drop it in some boiling water for the same time. Pull gently and it should just pop off. If the peg holes are different sizes, you'll either have to sand the hole to make it bigger or use some hot glue to make it smaller, check out the tutorial section for more info.

just to add...im referring to a female head transfer, to be more specific, a black canary dcih to marvel universe female body. thanks