In my opinion shell selection is a bit more important than choke selection, although if you want to optimize your patterns you will need the best of both. Still if it were a matter of wanting a good pattern and choosing between choke and shell because of monetary concerns I would go with the shells everytime.
If you want to extend your range a bit I would recommend switching your ammo to Hevi-13 3" 2oz #6's (about 420 pellets), or Winchester Supreme Elite Extended Range 3" 1.75oz #6's (about 362 pellets). Both should shoot well out of that diameter choke.
Hevi-shot is currently running a rebate which should make 10 shells cost around $22-$30 depending on where you buy them.
Good luck!

I just found an Indian creek black diamond choke for 62 bucks online so I went ahead and bought it. I think that coupled with the Hevi-13 #6's will tighten my patternat 40 yards significantly. Thanksguys for your help...