Long way from parts, mechanics, help, everything except cows

I have a '77 450SL, about 98K miles. On the passenger side of the engine, there was a pipe that ran from the timing chain tensioner to the diverter valve with a check valve on it before going into the diverter. I am in the process of replacing the air pump and need to find that pipe and a check valve. Right now, it looks like someone cut the pipe off, and blocked off the hole into the side of the block. I want to get this done before I start trying to figure out if I have a timing chain & rail problem. It looks like this has something to do with the timing chain tensioner pressure. Does this make sense to anyone....I think I need to find a couple of parts. I am in western Nebraska, I can't even find a wrecked 450SL to look at! Anyone have either help or an idea on this?? Maybe a place to get some used parts??Thanks.