Sleeving is the only option left if your Machine is dying & you cant find the New bore.
Sleeving if done properly. Boosts your Machines Fuel efficiency, your ride gets smoother like the Std bore, thers no vibrations from the Bore & overall its a nice feeling. This is the Upper side of Sleeved bore.
The Lower side even if the Sleeve is done very nicely, you cant expect your bike to perform like the Original, The Bike Heats very fast specially in the RX's family bores thers unusual knocking sound emitted if you try to rev it past 85 kmph (RX-100 Sleeved Bore) & it feels as if the Bike is choking & gasping for Air.
There are 2 turners in Mumbai who can get a good Job of Sleeving. 1 is in Gaiwadi & the other in Dadar. It can cost you around 1000 Rupees per Bore.
I personally have tried almost all the 2 strokers that I own to run on the Sleeved Bores & I am not satisfied with the Result.