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Before you go into all that expense (and it will depend solely on YOUR mechanic's abilities and shop policies), I would seriously recommend getting a can of starting fluid (available at most car parts stores) and using the spray tube, go over all of your vacuum lines (and there are a LOT of them!) and their respective connections by lightly spraying them. Wherever there is a leak, the engine speed will go up noticably, and that will pinpoint it.
I can't imagine that a head gasket will cause a vacuum leak, not without other indications anyway.
There is no vacuum on the heads except for the intake/head connection. If you have a vac leak it will be there, or carb base gasket if on the engine. There is a Bunch of hoses where it will more likely be leaking. The start fluid test is a good one to use to find the leaks.
What are the symptoms indicating a vac leak?
I dont think you would get a leak from the heads. Intake to heads yes but save yourself some cash and let a pro check it out. I wouldnt use starting fluid to check for a leak, you may end up with a bigger problem as in a fire, I would use carb cleaner and be very careful with it also. JMHO
One way to check for vacuum leaks is with a bottle of propane. Spray a little propane (unlit) near the source of the suspected leak while the engine is running. The idle speed will increase if there is a leak. (the propane is sucked into the engine and consumed as fuel).