The old one reminds me of the stuff Dixie Gun Works sold back in the 70's
most likely your tube was made by Hern Iron works, which means it does have a steel liner,
it is recommended that you bush the touch hole as water can get between the liner and the casting causing rust,
most drill and tap the hole and use a stainless steel bolt, once installed cut it off flush and you should have no
further worries in that department.
Allen <><