My experience with Powell is that the bass like movement and while I am sure they are opportunistic I feel they are very piscivorous. Wayne and others would know the answer to that. When I fly fish for bass I try to figure out where in the water column they are so I can get food to them. That is the reason you will see responses to line choice at powell so varied, it is all about getting to where the fish are. Smallies are in rock piles, period. That one is easy, although for the most part the smaller ones are up on shore...mostly. Sometimes there is a whopper an inch from a shore rock just waiting. They go where the food is. My experience with largemouth there is that when you find a good depth stick to it. While I love to stick big bruisers with a fly, it is hard to get to where they usually are, both in structure and depth, on the fly. I will pick up a bunch of smaller ones on the fly rod and then go hunting pigs with a spinning rod. Last, most lures are designed to catch fisherman not fish is the saying. To me, it may not be a certain variation of color or even type sometimes. We worry too much about the hot lure. It is more important getting a lure to the right location, and then getting the right movement. That is how I pick flies. Deep fish and I tie up a really heavy clouser and chuck and duck. Not so deep and my options open up a lot. Add the right line to the right fly and you get the desired depth. Trout flies absolutely will work at the right time. I posted a pic probably 10 years ago of a monster carp on a Size 12 royal Wolff. Maybe try a spinning rod to get location and depth, then figure out the fly combo that matches. Or just drink a beer and have fun. Or I could just be entirely full of "TR" lol. Tight lines.
TR