I shoot that exact same gun as does my wife. I like the 26" barrel and believe it to be the most versatile length.
I always like to see if there's a way to "fix" the current situation first, without spending money, just a little time. I'd recommend that you "deep clean" your barrel and would recommend the article, "Cleaning a Shotgun Barrel"
Sometimes, that's all that's necessary to improve patterning.
It has been my experience however, that with the particular shells you're shooting, a turkey choke with with both a longer parallel section and a tighter exit diameter will many times produce better, more dense, patterns. Chokes with e.d.'s of .640 to .650 have worked best for me.
So, my recommendation would be to try really cleaning that barrel (and choke of course) then patterning again. If that improves your patterns enough, you've solved your problem without spending any more money. If not, you may want to explore another turkey choke.
If I can help, please let me know and I'll do all that I can to be of assistance.
P.S. I'd also agree on the advice to try some #6 shot. It seems to flow much better in many guns.