First, I would say prior to dropping off the parts...Get yourself a disposable camera if you dont have digital. As you tear it apart, take pictures of everything the way it was BEFORE you took it apart. Take one of the brackets/pulleys, one after the valve covers and intake are removed, etc. Two cameras should do it, and you wont get crud all over a nice camera...lol When it's all apart, and you have "references", do some online research on how those aprts do waht they do, and more precisely, how the numbers are calculated and why. The reason behind the research is it makes you aware of what choices you'll need to make, and why the machine shop needs to do what it does. It will clarify some common confusions too. Like that compression ratio question.
If you are running open chamber iron heads, you will not want "10.5:1" in it. However....The piston companies will sell you a "10.1:1" piston, that will end up at a lower static ratio than 10.5:1 in your engine, and it will work fine. Ask questions. Keep asking "why?". If you cant get an answer you understand, ask again. If you cant get an answer other than "trust me", find another shop. Last, if you are planning to assemble yourself, you will need some tools. Not basic hand tools. Measuring stuff. So leave room in the budget for it...
There's no greater feeling then hearing/driving "your baby" running full throttle in a car...