Well, for the most part, if you are getting your build done by a good mech. then have him measure everything according to the FSM. Anything that isn't in spec or doesn't look to be reliable(or stuff that has gone wrong commonly with other 240's) you should replace. If it's in spec and checks out then just leave it. IMO you should get your head port&polished. I would do it...but that's just me.
I'd also look into cryo-treating some random stuff.