The crank is the only thing that changes the length of the stroke, but building a stroker is more complicated than that. I like the kit approach personally because a well designed kit will have rods and pistons with the proper length and height.
I'm currently considering building a stroker motor for my small block powered car because it seems the easiest way to both refresh the motor and get a little more power without requiring the work and engineering of updating to an LSx motor.
I haven't decided if I'll rebuild what I have or just buy a 388 crate motor. I might also just cheap-out and rebuild the stock motor stock...
