When changing the had gaskets, will I need to automatically re-machine the heads?

What is your question?

I just recently posted a question on here about my Outback recently purchased from the third owner. It has 140,000 miles on it, and upon purchase, it appears the seller lucked out in that the head gaskets had just started leaking. I am checking with a couple of different mechanics to see how good of a job I think they will do. I would like to know before consulting with either one the answers to these questions: The car has never over-heated. What is the maximum out of clearance the warpage can be for you to recommend having it machined vs. just putting in a new/less used set of heads? I have read that tolerences of .002" warrant machining; is this correct? Given the mileage on the vehicle I'm expecting to have greater tolerences than .002", but I'd like to know how much is too much to even warrant machining the head. Also, after machining, what else needs to be done specific to the machining ... do the bores need to be machined as well (can this even be done on such a small engine)? I already know the radiator hoses and pump, thermostat, valve gaskets ... etc., etc. should be replaced with the engine out, but I'm wondering if anything else needs to be done specific to the heads being machined. The timing belt was changed 20,000 miles ago, is it best I just go ahead and have that changed as well since it's going to be dis-mantled? Just wanting to know, to make a better decision of which mechanic to take it to.