Your revolver, apparently, is a Model 58. Unless modified, it has what is called an "N frame, square butt."
There are literally hundreds of aftermarket and alternative grips for your sixgun. I, too, find the small S&W stocks, called "Magna's", uncomfortable for shooting any S&W that produces much recoil.
The current grips come off the frame easily. Find a quality screwdriver that fits the screw on one of the stock halves. Loosen the screw all the way, then turn it back in a turn or two. Carefully press the screw down back inside towards the other side of the gun. This will push the far side stock half most of the way off of the gun. Gently remove it, and then the grip screw, and set them aside. You can then push the remaining stock half off of the gun from the inside side of the grip half, using your thumb. Slip the grip screw through the hole it went through, and turn its threads into the threaded escutcheon on the other half. Put them in a clean, dry box with other valuables so you don't lose them. You can replace them back on the gun at any time.
NEVER try to pry grips from the gun's frames with a knife blade or screwdriver; you will damage them.
Look at the many grip styles displayed in photos of the threads on this sight and you will find something you like, something a bit bigger to fit your hand better. A set of neophrene or rubber grips made by a comany called Pachmayr won't set you back much. They were the most common replacement stock for S&W revolvers made during your dad's gun's period. You should look for the variation called the "Presentation"; or a similar one with finger grooves on the front is known as the "Gripper."
You will like shooting the big .41 a lot more with grips that fit your hand, good shooting eyeglasses and protection that covers or plugs your ears!
I bought my Model 58 in August, 1978, brand spanking new, for $183.78 out-the-door. I intended to have a talented local gunsmith, the late Robbert Ballard, mill the topstrap of the frame to accept the S&W click-adjustable rear sight assembly, fit a new S&W Target Model of 1955, .45 caliber, 6-1/2 inch barrel and then rechamber the long, .41 Magnum cylinder to .45 Colt. S&W hadn't made such a gun as a catalog item, and those of us big-bore fans that wanted S&W sixshooters chambered for .44 Special and .45 Colt were scrounging up parts and N frame .38 Specials and .357 Magnums to be transformed into dream guns spec'ed out to our desires and the limits of our pocketbooks. Ballard had previously made me an ersatz 1950 Target 4 incher with a new/old stock S&W barrel, a new Model 28 Highway Patrolman, rechambering the .357 chambers to .44 Special chambers, and doing enough cosmetic work to the gun to make all the surfaces of the high-gloss barrel, satin blasted frame and cylinder all the same shiny gloss while polishing the donor gun's action to a state of wonder. I wanted a deluxe, target-sighted, double action S&W revolver in .45 Colt, and having gathered the doner M-58, new .45 barrel and adjustable rear sight assembly, it was just a matter of saving up the gunsmith's fee for him to create such a masterpiece for me.
While saving, I shot the M-58 'as-is' a few boxes. Winchester's full-power 210 grain JSP and Remington-Peters 210 grain swaged SWC at about 3/5 power both shot very well in the gun.
I was very, very happy to see writings in the shooting press that S&W was about to produce and catalog at least one run of 10,000 N frame target sighted deluxe sixguns in .45 Colt. They arrived in late 1977, as commemoratives celebrating 125 years of S&W, but we knew standard target grade .45 Colts would be along soon.
I sat the Model 58 aside. It would be preserved in it's original state, not chopped up into something else.
I couldn't use it for work, as we we restricted to .38 Special and .357 Magnum revolvers for on- and off-duty use. But this .41 looked to be quite the heavy duty brawler and I have remained very fond of having and shooting it on occassion.
Your father had excellent taste in picking out this rugged, no frills, no nonsense sixgun. For many years, the S&W Models 57 and 58 and their factory ammo were as close to ideal as possible for U.S. law enforcement belt guns for serious cops who gladly carried the extra weight in exchange for plenty of extra smack-down on the target when needed. Reliably expanding .357 Mag factory ammo was still a few years away and the .44 Magnum, as well as the 41 Magnum's JSP full-power loads, were too much of a good thing for most peace officer use. If more copshad been serious gunners than, the M-58 would have had a lot more commercial, and combat success