I think I need some valve work. I get some valve clatter when i accelerate or even at certain RPM while driving. No matter if its hot, cold, old oil, or fresh. I'm afraid of dropping a valve. I'v seen that damage and it's not pretty. Should I get a valve job? There is a place near my home that specializes in head work. Also, would it be worth my while to port, polish, and shave the head while it's apart? Looking for a little HP while I'm at it. Thank you!