Yes sir, the factory guides are an integral part of the head casting. When they wear out, the old ones are cut out and new ones are pressed in and then sized. OR as is being discussed here, bronze liners are installed. IMO, your best bet is to talk around and find a good machine shop in your area. There's too much dick measuring going on here to really get a handle on what might be best for you. That's becoming the norm for every thread around here, though and it is unfortunate.
