If the goal is to be able to use a spinning or conventional casting outfit with floating flies, then just get a couple casting bubbles. These can be used much like a bobber or filled with various amounts of water for weight to allow longer casts. Attach plain mono or fly leader, and use leader floatant solution as desired to keep the line/leader/fly floating.

There are also lots of poles that can be switched over to fly fishing. Often you can find convertible outfits sold as travel kits that readily allow use of two kinds of reels, etcetera.

Flyfishing is about way more than dry / surface flies, by the way.