WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
Building, troubleshooting and testing of these amplifiers should only be
performed by someone who is thoroughly familiar with
the safety precautions around high voltages.
50C5s typically run hot anyway. As for that connection, doubling the load at the secondary doubles the primary load as well. The shallower loadline will cost you some output power, but could also improve linearity. Just have to try and see.