You are leaning in the right direction with chokes, though for the purposes you mention, I would go just a little tighter, especially in the right barrel. I have found on wild prairie/mountain birds that I like something akin to LM in the first barrel, IM or LF in the second. Were it mine I would specify .012”/.025” choke for the right and left barrels respectively. I have shot this combination in double guns in similar conditions for years and think it’s about perfect. Incidentally, I have never regretted having a much tighter second barrel, and have many times be thankful for it.
As to pad, and I say this as a sporting clays instructor and gun fitter, I would avoid the “sporting clays” pads that have the heel of the pad cut at an angle. Some argue that this is to avoid snagging on mounting the gun. My comment is that in most cases this speaks to a poor technique. That angle reduces the pad‘a contact area at a point where it’s useful. I like Kick Eez pads, and would recommend their conventional black pad .7” thick. I would have the gunsmithing round the edges of the pad slightly.
This also is a chance to lengthen the length of pull, as most German guns, especially older ones, are too short for most people. Be careful here, though, as there is about a 3/1 rule in play in either shortening or lengthening a stock. The placement of the cheek on the stock will move about three times the amount added to or subtracted from the stock length. A small adjustment in length is a relatively large adjustment in face position on the comb.
As to ammo, I would choose a high quality one ounce load, probably #7 1/2. Get the lowest velocity you can; about 1200 fps is perfect. You might even find you like 7/8 oz. these punch above their weight in performance and are very pleasant to shoot. This promotes practice...and hitting!
Last edited by GF1; 06/11/20.
