I have the Model #917.273100 right after yours, year 2000. 22 H.P. Kolar Pro V Twin, with a 50 inch Mower deck.
Great Mower and I pull a Cyclone Rake Leaf Machine behind it plus a garden tractor trailer for yard work but No Plow.
I could see it being done with a few alterations and I understand that it would make it a lot easier if you could find one already together
with plow and frame. I've installed a few that I've adapted to my Mini Truck, 4X4 wheeler ATV, and even my Ford F-250 over the years and I've had a lot of experience with plow situations of all Kind.
I wouldn't hesitate doing it at all if I needed it and with that said I do have a few suggestions.
First Have you ever changed your Rear Differential oil? Sears doesn't tell you to do this but if you dig on the right Forums you'll find it's recommended by people who know! In my opinion Sears would rather you buy new diff. parts and replace broken gears and such. etc.......
A lot more info on the Hydro Gear web site,(they make all tractor Differential's for Sears Craftsman and many others). It's easy to do and the small filter is easy to find on the net! For mine Sears used 100 fl. (3 quarts), ounces 10w40 conventional motor oil,(standard), and #52114 hydro gear Filter.
Second you might need to add a small amount of weight to your tractor either in wheel weights or other method's. Hence the suggestion on changing your trans-axle, (dif.), oil! Plus tire chains as a suggestion as you probably already thought of.
With your tractor not being four wheel drive I wouldn't try to go much bigger than the widest part of the tractor, probably rear wheels.
I see that the Original Blade from Sears is 42 inches and I agree as that's what I was thinking.
Like webscrounger suggested The My Tractor Forum is the first place to start and maybe even post a wanted add for one.
I don't know what your talents are but for me if I couldn't find what I needed like for my Japanese Mini Truck I just built it all including frame etc....................But I have a lot of resources and Talent. I hope this was help full. Keep us posted.
Good Luck,
LtF