I was rambling around on the web after paying bills this morning and I stumbled across THIS LINK. Full of detailed drawings like this:
They also had a complete set for the Fort at Mantanzas, it appears I got a few things wrong.
All the drawings I ever needed, and tons of photos as well. I downloaded the drawings for the Castillo de San Marcos. Now I have no excuses
They cover lots of other stuff as well. take some time and take a look at the main page as well.