If you're thinking about going with the converted fly blank, the TFO BVK blanks in 10 and 12 wt. are real powerful for their ratings and have a pretty fast action for fly blanks. If I remember right the 10 wt. when tested using the Common Cents system spec'd out in the 14 wt. range, a Sage TCR 10 wt, spec'd out in the high 12 wt. range. Never had a 12 wt. BVK around to measure, but they say it's a real meat rod.
As fly blanks go the TFOs are a good value.