To be fully rebuilt I would say renew the oil pump and drive chain, and the crank & cam seals. Also valve guides and stem seals, crankshaft thrust washers, core plugs, dizzy o-rings, and possibly a few other bits I've forgotten. Of course with everything you can make a judgment on condition and wear as some parts may be within tolerance or have already been replaced previously and may be fine to re-use.
I just went for it and bought new everything, in for a penny!