curious as to what would be a minimum
and maximum line for a Canstar 196-7L rod

12-15# line is appropriate.
You can put 100# line on a reel and this rod...but if the question is what's appropriate, based upon the way the rod bends, appropriate drag setting, etc. then consider the piece a 12-15 lb rod. The 270 is a 15-20. Good, durable rod, a bit dated given use of better materials and design these days. But, still a classic and a rod with some history behind it.