NOt positive on the crank issue but i THINK everything is the smae on the internals. If you are buying a stroker kit it will come with the new crank anyways hopefully already balacned for your motor. The 347's of course produce a lil more power because it has more overall cubes. I've heard and i haven;t put mine together yet to speak for myself that they are famous for burning a lil bit of oil. The rod geometry for these kits is a lil more unstable but are great for low rpm torque. I really wouldn;t push the motor much above 6500 or so on a stock block. If you are wanting to build a high rpm motor for trsack use mainly you would one want to go with solid lifters and solid cam, two probably with a 331.