As Frank said, that serial is from the late 1960s. In those days you had three basic HW 55 models:
HW 55 S ("Sport"), basic stock, no cheekpiece, finger-groove fore end.
HW 55 M ("Match"), target stock, same basic profile shape with cheekpiece and checkered fore end.
HW 55 T ("Tyrolean"), target stock, famous high concave cheekpiece, checkered fore end.
Now Frank, Garvin, or Gaines will probably pop a gun or catalog up here that proves I'm wrong LOL, but as a rule of thumb you can tell the wood species by the style: the S is beech, the M and T are walnut.
There are rare examples of beech M's, and even T's, out there, but those are generally seen on older 55s in my experience. I suspect things were getting a lot more standardized at the HW factory by this time.
Beech wood can be instantly identified by the figuring of the medullary rays (channels which carry nutrients from the center of the trunk to the sapwood). On most wood species these are microscopic, but on beech, oak, snd a few other species they show up as large pale "flake" figures perpendicular to the grain. Their position on the stock will vary according to how the wood was cut from the log, but they are always there somewhere.
Here's a fairly subtle example, note the flakes above the grip on this 1950's HW 55 S: