You shouldn't have any problem. They're interchangeable.
well CJ says they have already selected the best tube based on the design so i have just kept 6550s in my two CJ 150 W mono amps.
now what i REALLY want to know is can my MV75A1s be converted to EL34s and triode like the MV60 and 55 can be!!
i have way too much power going on in that ultralinear 6550 thing happening. i want to hear what triode is all about. maybe Mr. Behr will chime in here he used to be a dealer for CJ i think in the 80s.