sounds like the older b-7 valve?
personally, if you don't have damaged female parts to the valve, i'd just return the c7's for some b-7's and a b7 wrench and be done with it by just replacing the more wear prone 'meat and potatoes' male part. a 10 minute job and no damage.
i'd definitely be into knowing any tricks too. you could break apart the old female valve with some work but doesn't help getting the new one in there, of course.
anyway, that's all i got. good luck.