At this time, if money is "tight" and you don't have a rifle on which to mount the 3-9x 3200 Bushnell scope, I would go ahead and use the 3200 on the shotgun even tho' it's a lot more "scope" than you need or can use given the relatively short range of the shotgun. You can leave the magnification adjustment on 3x while the scope is mounted on the shotgun... and that should work fairly well for you.
Eventually, I'd consider buying a 1-4x or similar variable shotgun scope with possibly a lighted reticle for the shotgun... especially if you get another centerfire rifle on which you can mount the 3200 Bushnell scope.
I've got a relatively inexpensive Bushnell 1.5-4.5x scope on my old style, semi-automatic Ruger .44 magnum Carbine that is, in fact, a shotgun scope.
It has VERY heavy crosshair wires that stand out well in low-light conditions that go down to a heavy wire "circle" in the scope's center inside of which the crosshairs thin down to "very thin" for more precision aiming...
not that an old/style Ruger semi-auto Carbine is capble of "precision" shooting.
The heavy "circle" not only tends to helps one to QUICKLY "center" the circle ON a moving target, but acts as a range-measuring device as well since the "circle" represents a 6-inch diameter circle at 40 yards and is parallax-free at 50 yards.
The scope has very thin crosshairs
inside the heavy circle in the scope's center to help the shooter to place the bullet with greater accuracy than might be possible with the very thick crosshairs. It is a
great reticle for taking running shots on deer in the deep woods with the variable scope on 1.5x or for taking more precision shots at longer ranges with the scope on 4.5x out to 100 yards or so... perfect for a shotgun having a rifled barrel shooting sabotted slugs.
Such "combinations" have been known to consistently shoot 2-inch, 3 shot groups at 100 yards... quite a feat for a shotgun which stretches the range of such a shotgun/scope combination to as much as 125 yards... more than enough for 95% of the shots most of us get on whitetails.
You have a wide variety of "possibilities" at your disposal... think about it, then do whatever you wish since there is no "wrong way" to handle this situation. Some solutions are just a little better than others.
Strength & Honor...
Ron T.