Howdy
Three hundred bucks for a nice old Smith like that is a great price today, if it wuz me I would grab it and run.
As Old Fuff said, those grips are easily worth $100 just by themselves.
Those are not Magna grips, those were known as service grips.
These are Magna grips (or stocks as S&W calls them). Notice how the grips rise all the way up and cover the corner frame screw.
There are about 4 different types of service grips that S&W put on their revolvers before Magnas. The ones in your photo are square butt, round top, without medallions. S&W used them between 1920 and 1929.
This 44 Handejector 2nd Model wears grips with recessed gold medallions.
This M&P wears grips with flush medallions.
If you buy the gun, be sure to remove the grips and see if they are numbered to the gun. Usually numbered in pencil, but I have seen the numbers stamped in too. Sometimes the penciled numbers have worn off.
I would not worry too much about loading six in that gun. Although I NEVER load six in a traditional Single Action, all S&W handejectors had (and still have) a rebounding hammer. When the trigger is released, a nub of steel on top of the rebound slide forces the hammer back about 1/8", pulling the firing pin away from primer underneath. Yes, it has been documented that on rare occaision the hammer stud might shear off under a tremendous blow and discharge the gun, but it was very rare. Much rarer than the 'safety notch' or sear of a Single Action shearing off, and requiring a much heavier blow. I'm not sure, that one may even have the old spring type hammer block inside, mounted on the side plate, not sure just when they started doing that. Even so, I have several old Smiths made before the hammer block, and I never worry about carrying six rounds in them, although I would never do it with a Single Action.
Grab it and run.