A word of caution -- if it HAS been in a house fire, and the metal got hotter than about 300-400 degrees (F), there is a good chance that the temper of the steel could have been changed. There are lots of other things that might cause the smell, but that one is worth considering.
I'd at least take off the wood and look at the inside. Wood begins to char at about the same temperature that hardened steel begins to soften -- any sign of burning in there and I'd be very cautious. If the magazine follower is plastic (can't remember if they are or not on that gun), I'd examine that for any sign that melting happened. Weakened springs are another good thing to look for. If you see any sign that the gun was heated in a fire, you’ll want to very carefully consider whether it is safe to fire.
As far as smell, you might try sticking JUST the wood in the safe for a few days, and then just the gun with wood removed. That way, you can see which one is stinking up your safe. Then you’ll know what to focus your cleaning efforts on.
If it’s the metal, you might try removing anything oil based from the metal by washing all the metal parts in hot water with soap (Dawn works well too). If you live someplace that has soft (and thus slightly acidic) water, mixing some baking soda in with the wash water will help prevent flash rust. Dry right away, and get some oil back on the metal. Acetone will accomplish the same, but it is more toxic and costs more. If the “smell” is dissolved in a coating of oil-based compounds on/in the metal, then oil based solvents like CLP won’t clean them off.
As far as lye goes, ANY soap will have lye added to the mixture when it was made, but if made properly, there should be no lye remaining. This is an acid-base reaction -- the fat is the acid (along with left over glycerin), and the lye is the base. If mixed in the proper quantities, all the lye should be neutralized. Dawn isn’t quite soap, but it’s based on sodium lauryl sulfate, which is in most ways similar. The idea here is to make it so that water can dissolve oil based compounds.
The drain cleaners DO contain lye – they work through a different mechanism. In this case, you would actually be MAKING something similar to soap out of the oily compounds on the guns and the lye in the Drano. This is why slightly alkali stuff is slippery – it turns the oils on your skin into a thin layer of soap. It is also how concentrated bases like drain cleaners can horribly injure you – they turn the layer of fat UNDER your skin into soap, and off comes the skin. Drano also contains significant amounts of plain old salt (it's a by-product of modern methods of manufacturing lye by running electricity through salt water) -- so make sure you rinse it all off with fresh water.