I would find another engine to build, so your car won't be down. You will most certainly want a 4-bolt main block. Don't rely on casting numbers. Take the pan off and LOOK. We've seen LT1s that weren't 4-bolt main.
For a 383 kit (ALL Chevy 383s are "strokers", so no need to say it), we use Eagle. We've found them to be of very consistent quality and they measure good. Avoid the cheepy-chugger cast cranks. As said previously, get a forged steel crank. There are various other vendors with kits, too.
ProCharger seems to be the hot lick this year!