I have to chime in here too.
I own three of their rifles and truly enjoy them. I spend more time shooting these than anything else. I have several Shilohs, and there is a lot of history and charm that go with the model '74 Sharps rifle, but the CPA's fit me better.
In regards to your question- what would I suggest?
If you intend to shoot black powder go with the .38-55 and a #4 barrel 30" long. If smokeless is strictly your thing the .32-40 is tough to beat. I would go with a #3, or #4 barrel again 30" long- maybe 28".
As long as I am spending your money order the .38-55 in the configuration I stated, and get the .32-40 as an accessory barrel.
My last thought- Get another accessory barrel 28" long, #3 weight in .22 rimfire with a rimfire breechblock.
There--- I spent it all. Just think of how happy I made you.
Psst- don't tell your wife.
Bruce