Can't say on the high nickel content, but the cranks are different on a 396 and 454. Basically a 427 is a bored out 396, and a 454 is a stroked 427. The 396 stock bore is 4.094", and the stroke is 3.76"; while a 454 stock bore is 4.250", and the stroke is 4.00". The length of the rods has nothing to do with the stroke, but contributes to the "stack" to get to the right deck clearance/squish. Your friend will be running a 427 if it's a stock bore 454 block and a 396 crank.