Based on some sage advice I received from forum members, some personal research in the "new to me" world of single shot rifles, and hours of discussion with a friend who is heavily involved in this sport, I have narrowed down my choices for a planned build on a Stevens 044 1/2 action.  As previously advised, my shooting would involve target work at 100 and 200-yard ranges.  In decending order of simple to difficult to get components for reloading, my short list is as follows:

32-20 - because brass and ammo is readily available
25-20 - for nearly the same reasons stated above
22 Hornet - for nearly the same reasons stated above
25 Hornet - will require custom dies and forming brass but 
                  seems easier to accomplish than the remaining 
                  cartridges
25-20 SS - a historic an interesting cartridge with a good 
                 reputation but will require custom dies and buying 
                 expensive brass
28-30 - a historic and interesting cartridge that has really 
            caught my fascination but again will require custom 
            dies and expensive brass

Of course the brass issue coud be overcome with breach seating, but for starting out I'd like to go with fixed ammo and a cartridge that wasn't so exotic as to make obtaining ammo too much of an obstacle (however I do see myself getting a 28-30 as second at some point down the road but only after I've started with a good basic kit).

As always, many thanks.  You guys are a tremendous wealth of knowledge and experience.  Your thoughts are greatly appreciated.

Jeff

I think that if it were mine I would go with .25 Hornet. Brass is plentiful and I should think that .25-20 ballistics could be duplicated, or nearly so.

Not being familiar with .25 rimfire bore dimensions, would it be compatible with simply rechambering the gun to one of his .25 caliber choices?

Of all  the cartridges listed, the .25-20 wcf would be my choice for numerous reasons. First of all the cost of getting brass, dies, molds, etc. to start with. Then it's well known good results for the 100-200 yd. distances you chose.
Finally it's a caliber that even loaded up a little faster, still produces very low recoil, and good case life.
And the .32-20 is a an equally great choice.

32-40 would be my choice. Premier 200 yard target round. A given at 100 yards.

O44 1/2 is to small for any cartage in the 32/40 class ken 

.25 hornet is a great cartridge. To form all you have to do is shoot.22 hornets in it and trim. 
Lee Gibbs pres.ASSRA

I should add that my CPA has a Douglas 10 twist barrel. (I like your Mission style furniture).

JerryH

Gail a CPA told me the 044 1/2 would be too small for any cartridge 30-30 and larger.  Hence, the list I came up with.  Thanks again!