Poor private, why the angst? Kabar was kind enough to answer your question and you seem to have jumped on him.
The morter you mention is the absolute low end of the scale. It is good for making noise and launching cans filled concrete, but not a authentic representative of a Civil War peice. It vaugly resembles a US Model 1841 24 Pounder. However, it is made of iron instead of bronze and the bore is only 2.25 inches instead of the correct 5.5 inches. It also is not chambered as per the original.
Ive done CW and other era reenactments since 1972. There are few events where a mortar would be appropriate. At those few events that might portray a siege situation, I can't imagine the Cheif of Artillery allowing a Hern Iron Works coehorn mortar to participate.
An appropriate repro bronze 24 pounder repro mortar tube will cost you $3,000+. If you can do the wood work on the bed you can save several hundered dollars.
Take Kabar's advice and seek out exisiting Civil War Artillery units in your area. Ask them questions about what is appropriate for the purposes you have in mind.
Now if you like the iron coehorn just to build and shoot for fun, you can get it for about half the cost directly from the foundry. Google Hern Iron Works.
Good Luck