i have a beautiful 1975 Nishiki Custom Sport which was given to me by its original owner and am in the process of replacing some of the components. i am tempted to go with shimano 600 for everything, keep the japanese theme alive. i would like to forgo a front derailleur and only use the larger chainring, i usually only use this when riding. i feel that this would clean up the look a bit. would this create any problems if i kept a 5-speed freewheel on the back?