Hi downsmith, I see no one else has replied so I will give this my best shot based on my experiences with my car. When I start the car in the morning it usually sits at 1100rpm when it is first started. I let the car sit for a minute or two and then I engage drive. The idle while in drive is 650 at rest. With regard to the rebuild of the heads I would guess that at that milage the motor would appreciate new seals at a minimum and guides and a valve job wouldn't go astray if finances permit. Go in there once is my motto. Hope you enjoy your car.