When I put an FB into a CTC-7 the support ring was very close to the anode connection, and arced over a bit. I solved the problem by taking two packs of high voltage putty and compressing it between two pieces of a Cool Whip top that I'd cut in half, and carefully wedging it between the ring and the area around the anode connection. Worked perfectly without modifying the mounting hardware. The putty is still available on-line from a few suppliers, including MCM.
Best of luck with your swap.
Kevin
p.s. It still might arc even if you are careful to use a "heavy duty" anode connector, whatever that might be... I tried a few different ones with no luck until the "Cool Whip" solution.