Only diffences would be pistons(NA have bigger dome=more compression=usually not good for a turbo'd engine) and possibly oilers squirters for the pistons(they come on 4g63t blocks but not 4g63, not sure if the g63b were the same or not). As far as I have heard/read the na engines came with the same crankshafts/rods as the tubo versions(this is hearsay and coming from the 4g63t world so may not apply to the g63b versions)