You don't need a new crank. You do need to sit down and map out exactly how much horsepower, and what sort of horsepower you want. Building a turbocharged autocrosser/street car is different than building a turbocharged car for the street and drag strip. You'll be running different tolerences and different components looking for power in different places. Figure a couple hundred bucks for the tuning, a grand or so for the Turbo, 500 for a new cast manifold or a 1000 for a tubular. Another grand for Turbo accessories and tubing. 1500 or so for an EMS if you don't have one. 500 or so for the dynotuning. 400 for injectors...

Rather than messing with sleeving an old block and all of that, save up an extra 2k and buy a Dart block. With the headache of buying and installing sleeves out of the way, you can build up the engine on the rack at your own pace. Granted you'll have to wait a little longer to build your dream monster, but it'll be a much better beast than trying to Frankenstein it. Then when it's built and ready, you remove your engine on a Saturday, install the new one on a Sunday, take the car to the tuners Monday morning, and they'll have it back to you by Wednesday.

Quick.
Clean.
Easy.

All in all, I spent about 15k on my "$3000" turbo kit. Then because I chintzed the machine work at a shitty shop, I only ran the engine for about 3-4k miles before it made like a grenade.