1960 Valiant Heater Core: what would fit?

Make sure to check your coolant system for voltage. I think anything over .05volts calls for a flush. Something about the cast iron/coolant flowing/ dissimilar metals/ poor gounds, all can lead to the coolant becoming electrically charged and becomes an electrolyte which can burn soft metals such as aluminum radiators and heater cores. I have seen this many times at the dealership. Heater cores! fun.