You are going to have to get with your vet on that one. I have no idea exactly how much calcium is in Tums or how much calcium your dog should have since he has his own specific needs. Tums should be fine, not the best form for the body to readily use, but giving it with food mitigates that anyways.
You want your liver to be 5% of the meat portion and the kidney to be another 5%. Heart and gizzard actually count as muscle meat and are really good to use as part or all of the muscle meat.
You may need to check your multivitamin and adjust things, like calcium, due to what is in the multi.
