There is a LOT of coolant in those lines and in the the heaters as well. The lines may also feed the heat/defroster in the front. Not sure how universal these systems are when comparing front-engine to rear-engine. On my rear-engine Thomas, I had to close 2 valves in the engine compartment to keep the coolant from flowing. Then, I disconnected the lines at the heater/defroster unit at the very front since it was the lowest point and drained it all into buckets and the shop floor. I'm sure there's an easier way. As for capping the lines, I used rubber corks with screws in them. Once those valves are closed, even if you trip the water pump switch, nothing will flow. Kepp in mind that if the system is connected to your defroster, that will not be in service any longer.
I will be rigging up my own defroster system, so I never planned on keep anything. Some of the hoses had to be cut off the connectors and I still havent removed all of the rest of the system yet. If you see a wire following those coolant lines, it most likely goes to the pump.