Friedman's world's naval systems says this:
Rim66A - range 32 km. entered service in 1967.
Rim67A - range 74 km due to a booster. (tested to 129 km range, though guidance was inefficient at such distances) entered service around 1968.?
Rim66B - range 46 km due to new, bigger engine (whole missile was longer than 66A) entered service probably around 1970.
Rim66C - range 74 km due to new guidance, engine the same as in 66B. entered service around 1978.
Rim67B - range unclear. possibly around 130 km, due to booster and new guidance. entered service in 1980.
Rim66G - range (almost) doubled, due to new engine. Could be then around 130-140 km. Entered service maybe around 1983.?
Rim67C - range (almost) doubled compared to 67B. due to new booster. 240 km?
All current versions of missiles supposedly have these ranges, even if their other components are newer. So unboosted SM-2 has range 130-140 km, while a boosted SM-2 has range of 240 km. The same figure applies for SM-6.
Only exception is SM-3 which has longer range still.
So... what all this is trying to prove is that, given all the technological advances we know of, which is likelier? That the hq16 missiles are stuck in 1970? Or that they are closer to where US was in 1978? Or are they closer to where US was in mid 80s?
Without any other proof (and 50 km range on a brochure is not really proof. It is something the manufacturer writes for the general public. It is the same as raytheon publicly saying amraam has range of 55 km while the real customers get briefed on actual capabilities that may be better. and yes, the same may be said for russian hardware too.)
I don't think it is unrealistic hq16 is at 1970. or even 1980. tech level when it comes to guidance techniques and rocket motors. And if so, is it more unrealistic to think its range is 50 km or 70 km or even 90 km?