All well and good. But where were the Southerners going to find all of the skilled mill wrights, pattern makers, machinists, jig & fixture men? To work at a skilled trade in a southern factory meant you could be replaced by a slave at any time. Ask the 450 men that use to work at Tredegar, replaced by slaves to lower production cost. With all the money that was made by the Southern Economy why could they only manage one large iron works in the entire south. Maybe this is one of the reasons that manufacturing, other than textiles, was very slow in developing in the South. Every ton of pig iron, every ton of iron ore, every ton of anthracite coal came from the North. Every drop of oil that lubricated a machine came from the Yankee whaling fleet or Pennsylvania oil fields. While the South was a bountiful agricultural are it was poor in resources necessary for heavy duty manufacturing. Like Japan, all of the manufacturing resources came to the South from somewhere else. You mentioned ship building in the South. While various species of ship building wood were readily available in the South, most of the iron fittings, steam engines, and propellers came from Northern manufacturers. Tredegar manufactured a few steam engines for the U.S. Navy, but never cast a propeller for a ship, nor did they manufacture iron castings for paddle wheelers.
Even with a tremendous amount of capital, the South lacked the skilled labor force and the raw materials to develop a serious manufacturing threat to the North. Forth years later, after the discovery of oil in Texas,iron in Alabama,
and bituminous coal for coking, the South would be in a much better position then they would have been in the late 1860s or 70 to launch a heavy manufacturing economy.
I've read some newspaper articles from that period between South Carolina declaring secession and the beginning of hostilities in April. The people to whom you refer were moving in to take advantage of the opportunities that were happening in Charleston. Hotels were booked. You could not find a room in the city. Warehousing was being constructed, and the business outlook was massively optimistic. Shipping companies were relocating to Charleston, and a whole host of Northern based industries were looking to get in on the action.
The money would have brought them.