Seems to be classified information. Had some time and looked around a bit for 76 RR production numbers. Came up zip. I'm fairly sure someone knows though.
As for specifics, like 318 4-speed, probably out of luck. Chrysler didn't keep very good records of those things as a general rule.
For how many survive, figure maybe 10% of RR's are living yet. Going by law of averages, that's about how many of any car are still around after 40+ years. Some cars more than that, some less of course.