Do you want to go tripple or double? Either way an old MTB crank will do nicely (i use one as a compact double on my vintage road bike)... if you go with triple I would go max 28 in the back. any old long cage MTB derailleur, any old FD realy, you can use anything... Of course if you want to get fancy you can use new stuff or find vintage stuff, I just pick through bins at the local co-op to replace parts.