Thread: How hard to port?

I've never ported anything before and I don't see a whole lot about actually porting our heads. Let say I picked up a set of L67 heads for cheap and wanted to build them up how hard would it be for me to do the porting myself. Or would it be better to have a shop do it, but if I have them do it how much would it cost. These are all rather general questions nothing specific really.