I had been able to identify the 7 Guns carried on the Ponchartrain as 2 32-pds rifled guns captured at St Charles AR. June 17 1862, These two guns appeared to have been taken from fortification on the Mississippi River defences north of Memphis when they were abandoned in March/April 1862. They are still on display at St Charles. two 9-inch and one 8-inch (Lady Baxter, on the Old Arkansas States House Museum lawn)Columbiah guns captured at Arkansas Post Jan. 11, 1863. The Confederates recovered one of these 9-inch guns and the 8-inch gun (Lady Baxter)from the well at Fort Hindman and refitted them for service at Fort Pleasent north of Pine Bluff. These were some of the fortifications that Selfridge was talking about "Running" in order to be able to destroy the Ponchartrain at Little Rock. Seems a little foolish to try that without good reason. These two guns were then moved back to Little Rock where they were captured September 10, 1863 at the Little Rock Arsenal. An two 8-inch smooth bore Columbiah guns placed again at St. Charles and moved during the attack on Arkansas Post to Deval's Bluff where they were captured on Jan 14th, 1863.
The two guns recovered from the well at Arkansas Post and refitted at least had the possibility of being remounted on the Ponchartrain to restore at least 2 of her original gun compliment prior to the Ponchartrains Destruction. And therefore could have made the Ponchartrain a more sizeable threat in Selfridges and Porters minds.
One comment By USN lt Commander Selfridge indicated that the Ponchartrain had 20 inch thick oak casements. She was a newer boat only about 5 years old and reportedly strongly built before she was fitted out as a gunboat ram at New Orleans in 1861. I wonder if the Union Navy thought that there was a possibility for the Ponchartrain to be rearmed and armoured? As it was the only surviving CS gunboat/ram north of Vicksburg after the destruction of the CSS Arkansas on the abortive Red River expedition of August 1862.