excessive crank case pressure.

new member. thanx for the join. I have a md 31c707 single o/h valve that seems to have excessive crankcase pressure. was way over full mark and I removed oil. turned over with the starter with the dipstick out and blew oil everywhere. removed cyl. head and cranked again. blew oil out the valve gallery about two feet in front of motor. any ideas or help appreciated thanx Doug