Jump on it. I was fortunate enough to own a 20 gauge Lefever Nitro Special back in Highschool and WHAT a sweet shooting double. Just lethal on squirrels and rabbits.
Now, the down side. DONT dry fire it. Parts havent been made for decades.
Something as simple as a firing pin replacement can be an ordeal. Mine had the screw that held the #1 barrels firing pin back out, causing the firing pin to fall inside the action. My Dad was able to get it apart, reinstall the pin and set screw, but he had to make a tool to reinstall the hammer. Such is life with older guns. As a gunsmith later in my life learned to live with working on doubles, but I never really liked it.
If you do buy it, carefully check that its not a damacus barreled gun, check for any rings or bulges on the barrels, and make sure the lock up is tight. You can close the action and gently try to wiggle the barrels on the frame. Carefully examine the ribs and make sure there are no areas where the ribs have loosened, or there have ever been any attempts to resolder them.
Check the wood right at the rear of the top tang. This is a very common place for the wood to become cracked or oil soaked. Pass if its bad. Think about it if its minimal.
Thats about it. If you get it, take care of it- they are great shooters. Pumps will feel clubby compared to this thing. Oh, the safety on the tang should be automatic- that is- each time you open the action and close it the safety will go to "on". Some have been modified later in life, so be aware of what it does.
FWIW I shot mine with field loads for its entire time with me. I probably shot a couple of thousand rounds with it.