In the Paramount the cathode resistor is different for 300B, 2A3 and 45 configurations. I have Paramours and they can be set up for 45s but it requires, again, a change in cathode resistor.
My guess is that unless you have it set up for a 45 you will need to make changes. It might very well work, but not as it should.
The plate choke and output transformer impedance for a 45 and a 2A3 are different if you optimize the circuit.