How do i fix a blown head gasket on a 1965 Ford Mustang?
I would recommend either buying or borrowing (some stores let you borrow, and some public libraries have them) a '65 Ford Mustang repair manual.
If the gasket is gone (it's just a thin piece of insulating material), replacing it is a pain, but not all that expensive if you do the work yourself. You will need mechanics' tools - which some stores will also let you use (AutoZone is one).
If the head is cracked, you would see more problems than milky oil. It's probably not water coming out of your tailpipe, either. Get the manual or take it to a mechanic.