Secondary connection is pin 4 which is 5k to the Eico 720. So what is the primary impedance?
Are you sure of the 5k figure?
I just calculated a load impedance of 2550 ohms for the 720's 6146's final and that is the impedance the 730 will be working into.
It appears the 2.5k impedance winding would be the better secondary winding.
Correction:
This would result in a turns ratio of ~ 1.2:1, for an impedance ratio of 1.4:1, primary to secondary.