Handi,
I don't think you could go wrong with either. However, there are a couple of points to consider.
The 7400 requires a little more maintenance than the Pump. It will come with a chamber brush. Most that are traded in are traded because they start failing to eject. If you asked them if they used their chamber brush to clean the gun, they normally look at you funny. They rarely are traded in WITH the brush. The 7400 needs a clean chamber to eject properly. Keep the gun clean and no problems.
The 7600 has an automatic (no pun intended) advantage, in that it is the same action as your shotgun. I have a Rem Model 141, the Pump that prededed the 760, chambered in, you guessed it 35 Rem :lol: . It is the smoothest, fastest gun I own. The 7600 is a good gun. It will probably handle reloads easier, extraction wise. Both are very strong guns. I wouldn't worry about reloading, or shooting heavy bullets (not sure why that would cause a problem). The 30-06 is a great round, and should handle anything you can find. Best of all, it's cheap to shoot, when it comes to major calibers. I think that the 7600 will be slightly lighter in weight, and probably a hair more accurate, but accuracy is good in both guns. If the 7600 feels good to you (Carries well, points well, balance, etc.) go for it.