My 12-year old daughter found a nice blue 1982 (I think) Murray bike she wants me to fix up for her. Frame in great shape, but wheelsets are trashed as is the one-piece crank. I have never done anything other than fix up a bike without changing parts, but now I have no choice (and it's time to learn anyway). Is it possible to switch over to a bottom bracket from the one-piece crank? Thanks for any and all help.