Jason,
In answer to Raimey's comments, I offer the following. I agree that a 12 ga. drilling is too heavy and bulky, noticeably so. Also, I would never consider a drilling in 30-06, even though it is one of my favorite calibers in a bolt gun. Not only would it add to the weight, a rimmed cartridge works much more reliably with a drilling's extractor. I have been hunting with drillings regularly since the mid 1960s and have reached the following conclusions : I prefer 16 ga 2 3/4" chambers and 60cm( about 23 1/2" inches)barrels. A scope is necessary to get full value from a drilling. For general use, i prefer a 6x42 with bright optics( I also have 8x56s for special use, but they add too much weight for general use). I prefer well fit "claw" mounts, but "swing" or "slide on" are also reliable. For the reticle in the scope, I prefer the typical German 3 post , but I used a heavy 4 post with x hair for many years and like it too. After those, any heavy reticle that can be seen in dark, deep woods is ok. You don't need to worry about "cheek weld", which is very important when target shooting, to get the smallest multi- shot group. Here, the idea is to be able to place one bullet where you want it. You shoot a drilling from a head up position usually. A drilling is stocked like a shotgun, because it is a shotgun. While harder to find, there are "Dural" ( aluminum) frame drillings, which are lighter than the steel frames. They hold up, because they have steel inserts in high stress locations. A "sling" is necessary, but never used for shooting( alters the point of contact). I prefer one of the quick shortening slings, that can be shortened in the stand to be out of the way. A rimfire insert barrel ( einstecklauf)( EL) adds to the utility, but should be considered "nice to have", rather than necessary, like a scope and sling. To sum up, I think you are looking for a 16 ga drilling with 60cm barrels, chambered for 6.5, 7, or8mm x 57R , with a 6x42 scope in quick detachable mounts. A proper sling can be bought later. There will be a lot of disagreement from others but you can have short chambers lengthened, and chokes modified to suit yourself. If the drilling is for your use, not for resale, and not an especially rare and/or fine one , there is no reason not to make it useful to you. In my experience, if you sell it later, there will be complaints regardless of whether it has been modified or not. This is usually an effort to have you reduce the price, or as an excuse for not buying it.
Mike