@dahattok Good choice on the 11 lber and I checked and it looks like you should be receiving it today!
Yes, using fresh pork bellies will be fine instead of ground pork, in fact it is preferable. Just remember that pork bellies are somewhere in the 60/40 fat to protein ratio so you can’t just add 20%. I’d say you are best off staying in the 60-70 Turkey Breast to 30-40 pork bellies.
I know you are wanting to use as much of the wild turkey breast as possible so the 70-30 will probably be the way you go. If that is the case make absolutely sure that you have very good protein extraction when mixing otherwise you are going to have some binding issues and you will “fat out” during the smoking process.
Let me know if you need anything else.