If it was me, do a search on Common Cents System pertaining to fly rod power. It's a simple deflection test using $0.01 pieces. Secure the butt of the rod, attach a sandwich bag using a paperclip to the tip, add pennies till the tip deflects 1/3 of its length, count the pennies, read the chart, done. I've checked all my fly rods and it checks out.
The issue is there is no standardized way to measure the fly line match of a fly rod. The standard was 30 ft of AFTMA line weight and rod deflection. With the improvements in graphite, most/all current day rods are way stiffer than yesteryear rods. Fly line mfr have followed suit which is why you see fly lines marketed at x times heavier than standard for X wt fly line. They are heavier because the rods have gotten stiffer. A fly rod throws the line therefore you need a certain amount and weight of line to enable the rod to throw the line. Plus people want to be able to cast 75 feet. False casting with a ton of line requires more rod power, hence a stiffer rod. Matching the line to the rod is fairly key. Experimenting with line works but at $100 a pop, I'd try to focus a bit closer to what the rod can handle.
