What's wrong with the panel if it works? Stick a new NiCd pack in the old bell job done, if the bell is operational.
As for fitting the new, you seem to have worked it out, red and white are connected to the same place so the same thing.
Engineer hold off wasn't really around when the 700L was made, so do with it what you want.
If your not sure, try wiring it up on a short wire adj panel before messing about up a ladder all day.