The attention is in the details. If you send two exact engines to the machine shop, one for a stock rebuild and the other for a turbo build such as yours, the paths they each take through the machine shop will quickly become much different from one another. There are many fine details and machine work that are necessary for the turbo engine that are not usually required for the stock engine or even a mild performance build-up, its not just in the parts alone. Getting your cylinders nice and round with a quality bore and hone job will also need a torque plate, but you won't need to do that to a stock engine rebuild.
O-ringing the block is also a possible upgrade you might need to perform. At the least, quality ARP rod bolts and main studs are one of those upgrades that are going to help make your engine last at this elevated power level, but also require the rods to be reconditioned and the block align honed. Adding those components is going to require additional machine work as mentioned to use them, adding more expense, but also an extra measure of strength and safety. Balancing the rotating assembly is going to be a another area you will need to explore and perform. As you can see, the machine shop bill alone starts to climb higher and higher almost at a proportion to the amount of HP you want. But when you start pushing the power levels twice the original and beyond, theres just more to it than bolting parts together.
