Google says 306A was the very first saw used. But that one should do the trick for you if that's what your looking to use it for.
Google also says 245a, found that out when I was checking Acres site. Some days it would be tempting.
I don't believe anyone on the wrong end of the saw would question the model number. I had looked a while ago and couldn't believe some of the prices they were asking. You got a cool old saw and a really great price.
We had a neighbor up at our cabin when I was a late teenager. He cut a lot of wood to heat their home and loved those Poulans.