What to tell the machine shop

Anytime you build or modify an engine, you have to do some measuring as you assemble. Clay checking the valve to piston clearance, spring installed height, rocker arm contact, etc. Do not overlook this. Read up on it, V8 stuff still applies to six builds. Shouldn't be a problem getting the head done first though. Just have a plan. If you're changing the cam, you will likely need different pushrods, usually one of the last things as head gasket, head milling all affect the length.