I really can't see you getting all of that extra work done for just 2,000. With the machining that is required to overbore, plus any other machining needed to be done is gonna add to the cost of the build. Also, depending on how much you bore, you will likely need a custom set of pistons, built to your spec.

Also, the lower compression pistons, and thicker head gasket are a great idea. But, if you want to go anywhere near 15PSI, I would highly recommend you either get new sleeves, or some type of block guard. Your best bet is to get the block resleeved, so that in the event you encounter a boost spike, your block doesn't blow to shit.

If anything, start with just having the bottom end built, and built right. Leave the head be for the time being. You can always do work to the head down the road. Removing a head is a hell of a lot easier than yanking the entire engine.