If RG213 is what you have, go ahead and use it, but be aware that at the higher frequency (440) you will lose
nearly half your power in a 50' run. 9913 has much lower loss but is hard to work with due to the stiff #10 solid
center conductor. RG8/U Belden 8237 would be a good compromise, easier to work with and less loss than RG213.
RG6 is another possibility if the 75 ohm impedance isn't an issue.