as far as the screw in choke goes, mine is a full...came that way 3 years ago.
as far as sights go, I had my local gun smith drill and tap my barrel for a weaver scope mount..cost me 50 with the base installed...if you go that route, make sure you trust your smith.
as far as shooting 45 colts from it at critters to 50 yards or so, you will find that you will get mixed results using 95% of the .45 factory ammo out there. the reason is it is almost always loaded for cowboy shooting and when you take the fact the overall length is less than 2 inches and the riffeling does not start for 3.110 inches (chambered for 3 in 410) you are jumping an unriffled gap of over an inch and then stuffing a lead ball down the tube when 50% of the powder charge has burnt up. they do shoot and are fun to shoot, just remember to take out teh choke before firing lead out of it. when I shoot cowboy loads I can watch the round go down range, and see it wable as it flies. That is what you get from 800 fps cowboy ammo.
But you can buy corbon 45 colt +P mag rounds and fro the reading I have done they should preform better from the colt...I myself reload my colts with 240 gr JHP from serria .4515 dia and am pushing the max amount of powder i can get into the case. I am hitting 1700 fps using colt cases..when .454 cassull are only hitting 1800 fps( yes you can shoot .454 cassull also, but they are more pricey than corbons 45 colts).
stock choice is up to you, and if you do ever get a sourviour and want to trade or sell the stock let me know...i could use one for the boys Handi.