I have collected a number of hull markings, including draft numbers, for 1/350 scale submarines. Almost all of these from resin kits (Iron Shipwrights, the old Yankee ModelWorks). I know of no source for 1/700 scale. The 1/350 markings are small as is. 1/700 DSRV markings would be minuscule.

One possible source is the old Dragon/DML kits. That said, as Bill says, most are not permanent markings. The DSRV docking markings, hull numbers, were all removed after sea trials. Operational submarines, to this day, carry only hull draft numbers.

One little realized details for modern submarine hulls is that due to the hull curvature (round hulls in cross section), draft markings are not equally spaced and sized. They have to accurately reflect the actual draft of the hull. Noted submarine expert Jim Christley has just written an encyclopedic article on this topic, with graphs and calculations of the proper hull number spacing and size for the different hull diameters of current and recent submarines.