I thought I should post a follow-up since you guys were so much help in figuring out what to do with this gun. Then the site went down. Now that it's up again, here's a short report...
When the gun showed up everything looked good. By my dating it was made in 1944. I'd be curious to hear about how a 1944 Spanish gun ended up in rural Colorado. Might be a really interesting story there.
It locked up super tight with the lever still a little to the right. The gun was just plain dirty, there was a little oil in the head of the stock, the recoil pad was hard, and the foreend was a little loose. The chokes were also a tight modified and extra full. In the gunsmith's words, if I managed to hit anything with it there wouldn't be anything left to pick up.
I took it home and started working on it with Kroil and steel wool. When I started to feel high from the fumes I looked at the Kroil container. Turns out it causes cancer. I sent it out to the garage and started using steel wool with WD40. Underneath the grime there were indeed wood and metal.
I put some of the finish repair stuff someone suggested on the stock. It worked well. I then tried clear shoe polish, but that seemed to cloud the finish even if I really tried to polish it.
After taking a break for a few days, I went down to my local furniture repair shop and picked up a can of Briwax with a little bit of red tint. It worked much better than the shoe polish.
To fix the loose foreend I put two pieces of weather stripping on the top of the foreend wood. The foreend is now perfectly tight.
Off the gun went to Bob Odenthal. He installed a new decelerator pad and opened the chokes to IC/Mod. I asked Bob about the oil in the stock. He just shrugged his shoulders and said to go shoot it.
I ended up spending more on cleaning products and gunsmithing fees than the purchase price of the gun, but the end result was still a reasonably priced 6lb 13oz, 28" barreled, 12ga field gun. Certainly a basic get it done sort of gun, but a solid shooter.
I took the gun out the day after picking it up from the 'smith to "test" it. I only checked one of the barrels, but it worked well.
Thanks again for all your help.