Definately have the chain replaced on the right side. It' easily done while the head is off.
I think their quote is a bit high. Tell them OK if they throw in a chain replacement as well, at the same price. (it's only about a $26 part to them) Well, maybe that is asking too much. Tell them you'll pay for the parts but not additional labor. The chain guides and rails should be replaced as well, as they get brittle and could cause a chain break. If you must, give them one hour labor to change the chain. It should take them 20 minutes.
Why do the guide pins have to come out. Can't they stay in?