The problem with these more modern EMU's like the Cl314 is that they will really only be candidates for static exhibition. Unlike the 1st generation of DMU's and EMU's they cannot be loco-hauled with passengers, so unless a heritage line is thinking of installing 25kV AC OLE there is limited attraction for such concerns to hoover up units of this era.
I think the best bet is to get behind the efforts to preserve a Cl313 at the NRM. It is unrealistic to assume that at least one example of every class will be saved, but at least there will be an example of the same family of units preserved.
O L Leigh