ARC with CJ?

Why would anyone want to ?

I've never tried to, so I don't know.
However, back when I sold high-end, including ARC, neither ARC, nor CJ, ever let the same dealer carry both lines. At the time, no other tube product company of which we were aware had such a policy, so it was kind of weird. Like two different religious sects that hated each other.
As such, I never tried the two in combination with each other, which would have been heretical.
Although, since they never even made face plates that could match each other in color, mating the two brands seems dubious.

CJ amps have 100K input to accommodate tube preamps. Any preamp therefore should work if the gain is reasonable. My experience, however, has been that CJ preamps have excessive gain when used with CJ amps. Go figure.

Why would you want seems like a good question. Not that it is a bad match, but it seems to be a combo that few would pursue.