What could I expect from just putting rings on?

[bignastyGS]

After blowing up the 14 hp motor on my 1200,I took one of the 12 hp's we had from a parted 1250 and installed it into my tractor. I know that this motor was used well by the PO and nothing more. It was free and seemed to be in decent condition. After installing it,it smoked alot when it started up. It had a stuck valve but we had it running before we parted the tractor last spring. I believe the stuck valve was just as of late. When I took the head off to see if there was more trouble I seen the gunk and so forth that was accumulated on the piston and valves etc. After a thorough cleaning,I reinstalled the head with new gasket. I also looked at the cylinder bore and it showed no apparent trouble spots. I tried to wiggle the piston and it seemed like it had minimal slop. The top of the piston had no apparent detonation trouble like the on in the 14 hp did. Since I know nothing about the motor,I was thinking of maybe just purchasing a new set of rings to install to see if I can get the smoking to stop.I have already added marvel mystery oil in the crankcase and put some seafoam in the gas to see if that helps. The smoking has cleared about 1/2 already,since I had used it last week to plow snow in the driveway. It seems the more I use it,it does it even less. I was looking for if it doesn't completely stop,if adding the rings would help at all? A couple more points I need to bring up is,this motor had a vibration at first start but now is smooth,the clacking or knocking noise has been eliminated too,form what I have no idea. The oil is clear as a bell and is staying up to level,which leads me to believe it's not consuming alot of oil. It is not gas and blows blue,but when you smell it,it's definitely oil smoke.The motor idles so sweet too. When I had the 14 hp on it,it shook at idle.With the 12 hp on,it has none of the shaking or vibrations at all.This motor has good compression and plenty of power. At this time,the tractor is a dedicated snow plower and I will use the LT1042 as my mower,I just want this one to play with in the snow and perhaps pull a rear plow. I would appreciate any opinions as to what I could expect if I would do a ring swap alone. Since I am 3/4 way done with my JD H and have to finish the out building on the back of my garage for tractor and pellet storage,I don't have the extra $$$ to overhaul this motor. I would rather get a 16 hp motor and do that over before spending the money on this 12 hp.So,what are the opinions??You wont hurt my feelings if they are negative.