If you count the # of cogs, you actually are running across more cogs w/out rub than yer 6spd setup. Remember the spacing on modern hubs is wider than yer old stuff and also those arent good combos anyway becuz of the wider range. Some tweaking is possible (limit screws, cable tension, etc..also ensure cage is parallel to chainrings) but there are limits to these systems. Refer to Shimano's install instructions and youll see those combos arent recommended becuz of potential for noise and also premature wear on rings, cogs, and chain. Not drastic of course but still possible.