Measure the bores of those barrels, with a caliper, Hacksaw, so you know exactly the bore diameter of each when you order wads. Just because it says " 12 gauge" on the barrels does not mean the bores are actually 12 gauge( .729") You may need to order larger or small gauge wads for it, or different wads for the two barrels.
It is very difficult if not impossible to force Over Powder wads( OP), and Cushion wads through any kind of choke tube. A better idea for loading would be to use only OVERSHOT ( OS) cards, which are about .010" thick, have a slick surface like shirt backs, but can be bent slightly to get them through the chokes. Once through, your ramrod and jag will turn them 90 degrees to drive down the barrel. Use 4 OS cards over the powder, putting holes in each card with an awl to let out the air. Orient the cards so that no two cards have holes that align with each other. Orient them at 12,3,6&9 o'clock. Put your shot load down then, and then put 2 OS cards, again with holes in them to let out the air-- the holes need to be off center but not so close to the edge that the edge will collapse as the card is pushed down the barrel-- to hold the shot load in place.
To lube, run a lubed cleaning patch on your jag down the barrel after seating those final OS cards on the shot. The advantage of this procedure is that by eliminating OP wads, and cushion wads, you don't have to carry an assortment of " Stuff " into the field when you hunt. You can even pre-lube patches and carry them either in a brass can, as I do, or in a ziplock bag, as I would do if they had been around when I was solving this problem for myself. ( I now carry a plastic bag in a pocket to put my used patches, rather than litter the ground with them.) I carry dry cleaning patches in my pocket in my hunting bag.
For good loading advice, check out the article by V.M. Starr, who was the dean of ML shotguns.
[url]
http://members.aye.net/~bspen/starr.html[/url]
These may seem light to you, but they work.
Use your Improved Cylinder choke tubes for hunting quail, and dove. Modified will work for hunting Pheasants over dogs, grouse, and chukkar. Late season anything, when the birds may not hold , can call for Full choke. Full choke is what you would choose for Turkey, as you are shooting for the head and neck, and not the body. Because you are NOT going to get the same velocities out of Black Powder loads that you get from smokeless, consider using a shot size that is one size larger than what you would choose in a modern shotgun load for the same purpose. Its the weight of the pellet that carries its energy down range, not velocity, which is shed faster than water off a duck's back!