If you're going to fish your Mitchell 300, you ought to stick with one of the rods that were commonly used when the 300 was at its peak. My first steelhead was caught on my own 300 when it was attached to an Wright McGill (Eagle Claw?) Powerlight (yellow fiberglass) model rod. Mine was 7 1/2 feet long, but the rods came in all sorts of lengths and actions. Another good choice for you would be an old brown Fenwick FS 83, or an FS 79. All were great rods for their day, but the Fenwicks were a little too expensive for me way back in 1969 when I got out of the army - sold for about $39.95 if I remember right. I caught a LOT of steelhead on that old yellow rod.

I like your idea of using your old Mitchell again. Mine is still buried somwhere in my garage.