Head Porting basics

Well the plan right now is to practice on an old set of heads and if I feel confident enough with what I've done I'll try it on the X heads, if not my dad and I both have heads we'd like ported and a local guy does nothing but porting, we may try to work a deal with him on some work just to know that our heads will be right, with how rare these heads are and desirable for resto guys I'd feel bad about ruining some, and worse about ruining two sets lol