[MrPbody]

You will need: A 400 crankshaft (SBC) with the mains ground to fit in the 350 block (BTW, I don't have a 350. Well, I do, but not my own use, but for guys like you, that WANT a Chevy, so no, not EVERYBODY has one...(:-). Also, a set of 400 rods would make the 350 pistons fit, but you're better off to use the 350 rods and a set of pistons MADE for a 383 with the 5.7" rod.
You might consider the several makes of kits out there for this application. We use the Eagle kit, as it has all the good stuff without compromise. There are cast cranks and forged cranks readily available aftermarket. Avoid the cheapie cast "steel" cranks, and do not confuse them with the "forged" steel cranks, which are the cranks people are refering to when they say "Steel".
There is a significant amount of clearance issues in the crankcase, and between the cam lobes and the rod bolts. This portion is best left to an experienced builder.
Be warned. Cheaper is NOT better, especially when you're changing things around like this. And getting by will only get you in deeper. Do it right and be done with it.
If you have high performance and high RPM in mind, use ONLY a forged crankshaft. If it's a street machine, more for fun than serious performance, use the Chevy crank, modified to fit. If it's a pickup, that will never see 5,000 RPM, go ahead and use the cheepie chuggers from China.
If you would give a little more detail about the intended use, I could be more specific. Just finished a short block for a local. It's going in a '62 "box" Nova (Chevy II). Nice piece. He still hasn't decided which heads, but he's spent $3,600 to date. That includes his short block, oil pan and windage tray, and timing cover. It has the Eagle kit with H-beams, forged crank and SRP forged pistons. NOTE: the H-beam rods take a little of the trouble out, as they make it easier to "clearance" everything.