First of all, is Batfish still owned by the Navy? The Navy inspects Torsk every year and one of the things they check is to make certain there is no power applied to the galley ranges. The ranges were always a fire hazard and required A LOT of attention to make sure they were kept clean and that no grounds developed.
The ranges are a resistive load, so they can actually run on AC or DC. To run on AC, you'd have to isolate them from the DC switchboards, but that requires removing fuses and running some new cable to the load side of the fuses.
Before you do anything, you had better meggar all the DC busses. The power cables developed grounds in well maintained boats. Figure the odds that in a boat as old as Batfish no grounds have developed. If you power up, you will have to meggar the busses regularly, at least once a year. It doesn't take long for grounds to cause fires or shock hazards. It is best to keep a record so that you can look for trends.
On Torsk, the DC shore power came into the Forward Aux DC Switchboard located in the Control Room. Can't speak for the Batfish. The wisest course of action, is to draw up your electrical distribution system before you try to bring on power. Try to locate some qual drawings or use the hand over hand method to figure the system out. You will absolutely need a system drawing for many reasons, so make one. If all else fails, start with the one in the fleet submarine and modify it to reflect the actual Batfish system. It will be incredibly dangerous to power up the system before you know what it consists of. Also dangerous if the system isn't meggared. Make sure all the fuses in the panels are removed before powering up. This project will not be completed soon if it is done right. Believe me, DC systems with DC motors are a maintenance nightmare. We had a large "E" Div on the boat and everyone in the Division worked constantly to keep things safe and running. Don't think you are going to do it with one or two people. It is doable, but I want you to be aware that you have a lot of work ahead of you. If someone has cut out pieces of the bus cabling, the job will be even bigger.
So, for starters,
1.) Document the system. Make some good drawings that show the system layout including all the power panels and junction panels.
2.) Open each power/fuse panel and circuit breaker and controller, thoroughly inspect it looking for damaged wiring, insulation, hardware, etc.
3.) Thoroughly clean each power/fuse panel and circuit breaker and controller, cleaning out any rust and dirt. Clean fuse contacts, starter contacts, and tighten loose hardware.
4.) Pull the fuses for all motors. Before you power up any motors, the windings will have to be checked for grounds, the commutators will have to be cleaned, and the brushes will have to be checked. DC motors use carbon brushes which wear out and the dust causes grounds.
5.) Meggar all DC busses and any DC loads you intend to power up. Keep a record of these readings. If any busses or loads show low resistance, go back and clean and inspect until the source of the ground is found, removed, or repaired.
If this sounds like a lot of work, it's only because it is. Get yourself a copy or Electrician's Mate 3&2 and 1&C and read them. They will give pointers on electrical system maintenance.
Please take this project slowly.
By the way, the DC Emergency Lighting System (the green, pressure-proof light fixtures) is a completely separate system from the DC power system. It is easier to get on line than the DC power. There is a disconnect in the Forward Battery Well and one in the After Battery well that conencts DC power at 250 VDC to the port and stbd emergency DC lighting busses. You can connect your battery at these disconnects and power the lights. Actually, there is a port and stbd emergency light junction box in after battery. If you remove the covers from those boxes, you can run a jumper from the port bus to the stbd bus, and power all the emergency lights from a battery in either forward battery or after battery. This would be a good place to start your power up project. It is a small system (relatively speaking). You still need to meggar the busses, check all the light bulbs, but it won't take a long time. Attached is a simplified drawing of the Torsk's Emergency Lighting system with the non-historic jumpers, batteries, DC rectifier, and lighting contactor.
Hope this helps. It would take pages and pages to describe things in more detail. If you ever get the chance to come to Baltimore, we can show you some of the things we've done to restore power. I can tell you that it tooks us years to accomplish the things we've donw and we still have a long way to go.