Your cross section is looking better and better. Looks realy good, you are making the best out of this kit.
Bilge pumps:
I found another photos, which are showing the actual pumps in a better way
In addition I took a look at the book of K.H. Marquardt in the Anatomy series.
Here Marquardt is showing on page 79 in sketch E4/1 Chain pumps and not the actual pumps which can be found now on the ship.
On page 27 he is writing:
"The current pump system is even jounger (before he is writing about the rudder) and would not have been installed before the middle of the nineteenth century.
Before this date, as indicated on the Admirality draught of the Royal Navy prize USS President, bilge pumping was performed by Chain Pumps, and the deck-wash water was lifted via elm-tree pumps from a cistern system. Sea water tanks were located on the orlop deck and connected via copper pipes to outboards below the waterline."
So unfortunately no better info in this book.
I think I have somewhere another book describing the Old Ironside, I have to check where it is....