I've never been a fan of overlining a rod, but if that's your thing, go for it. Overlining slows a rod down considerably and doesn't give a lot in return, IMO.
I've got a 3wt older St. Croix Legend that will chunk a size 14 fly all day. I've got a Teeny 2-3wt line that does a great job, and a 3wt line from LL Bean (goes to show you how much I use it) that is also great.
I built a 6ft 2wt rod from H&H that's great for about 25-30 feet and #16 and higher flies with the Teeny line, which slightly overlines the rod. But I don't use it nearly as often as the 3wt rods I have. Thing about a 2wt is it's not nearly as versitile as a 3 or a 4. You've got to use small flies or you overpower the rod.
When it comes to rod weights, I believe it's not the size of the water but the size of the fly you intend to cast.
