The ID plate is to the right and slightly below the fuel pump. Because of the steel fuel line, alternator with integral voltage regulator, and the fact that it's mated to a 280, I suspect that it's a 130D. As Kenny mentioned, these engines are reliable and easy to work on. No choke on the carbs so keeping it in tune is a must. Carbs are easy to rebuild but intolerant of debris in the passages. Tune up parts are surprisingly expensive. I went with an electronic switch replacement for the points and it's much easier to start and perform maintenance. I use Hot Spark but there are other brands out there.
Let us know how you're doing with it.