[Seaman]

I'd guess that it was originally a marine or industrial engine. That's why you can find it listed in the automotive reference. I used a marine 427 in my car and I put the engine tag back in, even though it now had dual quads, different heads, and higher compression. Very few engine tags are still around, so I put it back on the carb stud. You might be in the same lot. I couldn't find the number either at the time.
If its BRG and in the Yakima area, could be my old car.

Enjoy.