I know it’s not a finesse reel but what’s the lightest lure you’d throw with yours? What’s the heaviest you’d go? Anyone put one on a rod with a light lure rating? I also know that the rod casts the bait but the reel plays a part as well. 

Curado K is a workhorse reel intended for lures over a quarter oz.  Above that, your rod is the only limiting factor.

Unless its a pretty aerodynamic bait, not much under 3/8 oz. As much as people love the new curados, they arent as good all around casters as some previous gens. My E's can cast 1/4 cranks a long way with the correct rod loading. The K wont touch them on the lower end.

I had a chance to fish my K 8.5:1 toward the end of last season, spooled with 15lb Invizx on a 7' MH fast tip Carbonlite and used it for a KVD Caffeine Shad, weighing in a  little under 3/8 oz.  It was perfect for me.