Ok, I just did a good hour and a half reading about this so I'll regurgitate what I just read.

Stock crank = 2.1 inch journal = 3.622 stroke
2.0 inch journal = 3.71 - 3.72 stroke
1.888 inch journal = 3.822 stroke

You need to find rods that are in that journal size. You'll also need custom pistons. If you know where to search you can find the rods rather cheaply. From what I read having a crank redone ranges from $150-500. You need to make sure they put a good radii on it to help with the small journals. All of what I read sounded rather positive.

 

Well i was going to build a 370 with a stock crank ....I will have to do some math but what about a 408 " 4inch stroke" piston, find a longer rod not sure in the lenth yet and then offset the crank to match , it s going to be close to a 6.5' rod...Let me do the math