Every engine I have pulled the dowel pins or pegs are guides. Sometimes it takes a little persuasion to seperate the engine from the bell housing.
The last engine I pulled, a 350, I gently used a crow bar. The problem in this case was one side wanted to come off easy putting the engine and bell housing in a bind. I reinstalled a couple of the bolts to bring the whole assy. back together and then made sure both sides came back apart equally.
