I wonder about the upgrade also. The original tubes perform well and can last nearly a lifetime if treated properly. The conversion will also reduce the price should you decide to sell down the road.
I converted my T4XC's to 6146's way back in the 1970's, even though sweep tubes were plentiful and cheap. It was a very easy conversion, and did not require choke changes or anything else. It was very easy to change back.
The only changes necessary were the tube sockets and caps, one capacitor in the neutralizing, and a resistor in the bias.
The only tubes that fit were 6146's using the stepped-in base. As I recall, that was because a tank lead or something else ran past the tube base near the chassis.
I absolutely did not change the plate choke or anything else, it was just sockets, bias, and things related to the different P-G1 feedback capacitance.