Ditto the pic of that fly !

I like a hairsear nymth for crappie and gills. I use a spider pattern 98% of the time on gills. Floating line with both patterns.

How far do you cast to the Gills?
I like to keep it under 30'

I don't think I ever got a rise out of a spider or a Dragon fly.

With Rainbow, you want to keep the fly small. I dont know about the hook size or Fly (Gob) size with Gills.
But Crappie are what I'm after. She'd deep fry those pesky little Gills if I brought them home, but its like trying to eat a Porky Pine. All spines!
Show a photo of a couple of your Gill Dries.

Reading about fly fishing gives me the itch to try again as it is always fun to try. I would amagine I need to change the line as it is about 5 years old. I just changed the line on my regular poles after a cat fish broke my line twice.

I doubt if the Fly line would break but you'd sure want a new Tippet and leaders.
I test them on the boat, hook something and rear back with it to see what gives first. You always hope the drag or you fingers are smart enough to give just in the nick of time.
Be sure you re-tie the knot at the fly after you test.

strike indicatiors ,poo.