I'm putting together a bike with what I have laying around. I have a 3 X 8 trigger shifter set but my wheelset has a 7 speed freewheel, shifter and freewheel are both Shimano. I don't want to buy a different shifter set or wheelset. Can I just set the shifter in the 7th gear position and set the high derailleur stop and cable tension to keep the shifter from advancing to position 8 then set everything else as normal? I'd cover the "8" on the shifter so if someone else rides it they won't try to force it into 8th and damage the cable.