For anyone with normal eye sight, only low magnification is required for a 336, with any of the cartridges chambered for it. The old quality fixed power scopes like the Weaver K2.5, or the Bushnell Scope Chief of the same 2.5 power, are in my opinion absolutely ideal for a Marlin 336. Some of the assets going for them is better eye relief and great field of view.
For a clincher on this subject, Kamlooky, who is a great devotee of high rating variable scopes, fell in love with the Texas Weaver K2.5 scopes on my Marlin rifles, to the extent that when we pack up to go home I count my rifles, to make sure one of my 2.5 power scoped rifles is not in HIS vehicle!