89 Toyota 4Runner

Hello,

I have a 1989 Toyota 4Runner with the 3VZE engine. Took it to a shop due to loss of power and i was told it has an exhaust manifold leak on the passenger side. I was quoted $450 to take the Manifold off to further diagnose the loss of power. My question is, knowing the reputation of this engine, should I have the shop tear the engine down and due a head gasket service and get my cylinders resurfaced and valves adjusted? I do not have any coolant loss and no coolant in my oil or in my radiator.