From all my research into two stroke cylinder design, a steel sleeve is strictly for engine longevity. In this case the ability to re-bore and hone the steel sleeve, as well as the ability to use chrome plated rings extends the the useful life of the cylinder.
For maximum power output (obviously not what it seems the OP searching for) a steel sleeve will always be at a disadvantage to a plated aluminum cylinder. This is because of the poor thermal conductivity of steel (relative to aluminum) compounded by the fact that even the masters of Japanese 2 stroke manufacture could not create an efficient thermal bond between the steel sleeve and the aluminum cylinder that does the cooling in an air cooled engine.
One effective solution for this is water cooling, obviously.
So I would venture to guess top end longevity would be significantly improved with a water cooled, steel sleeved cylinder.
Of course you would then need chrome plated rings that fit our piston. And if you plan on over-boring that sleeve you are going to need to source a similarly larger diameter piston somehow (not impossible, just has to be done).
Ohh yea, and the whole water cooling system...
Water Cooled Steel Sleeve Cylinder Kit (puch/gilardoni/hi hi?)
Water Pump (engine has to turn this, robbing HP, and you need to design a method of attaching it to the engine so it can then be driven with a chain, or gears, or a belt)
Radiator (again need to design a method of attaching to the frame, and routing the lines, plus: water is heavy)
There is another way.....
Nikasil plating instead of the BS China single step chrome plating. Heck even a legitimate high nickel content chrome plating would be worlds better than what these cylinders come with from the factory.
Now both roads have their expense, but I would recommend accurately removing the existing BS chrome on a stock cylinder, and then have it re-plated with high quality chrome -or nikasil- thick enough to create a nice tolerance gap for the piston you intend to use. If you use chrome plating, then you should use the stock cast iron rings, witch you will have to replace much less frequently with a harder cylinder bore (the cylinder won't wear nearly as fast, so for the same amount of ring wear, the cylinder the the harder bore will still have a tighter ring end-gap, and thus will retain higher compression, longer).
If you go the Nikasil route, you could use chrome plated rings if you wanted to (and could find them for the piston you intend to use) and get even longer life out of the top end.
Now I haven't found anyone to do this for our cylinders yet, but I plan on looking. And I wouldn't be upset if someone else found a place to do it and you know, like....
...posted it here.