About a decade ago, when I was beginning to get curious about spey rods, I built a fly rod on an 11 1/2 foot G. Loomis graphite spinning/casting blank. I finished it with a short permanent butt, a long full wells handle, and a little upper fighting grip (about five inches long) a short distance above that. If I was doing it again, I'd build it more like a short spey rod, with a long enough lower butt to get a good grip on, and a long but nicely tapered upper grip. In effect, it was what is now called a switch rod. It casts beautifully with WF10 lines. I had it out and was trying it again recently. I think I'll try it during this autumn's chum season on smaller rivers. A blank doesn't "know" that it was designed for one kind of line or another. If you're willing to experiment, there are many more suitable blanks than were designated for fly rods.