The best thing to do is NOT sleeve them with a steel liner, they dont wick or transfer the heat away from the piston as fast and they will need richer jetting to keep the piston cool. You can have them either rechromed or go with nicasil plating like the new sleds run. The chrome plating was not a very durable coating, hard to seat rings good to it, liked to flake off and ruined crankbearings. The nicasil of today works excellant and can be run with the rings, youll need to send in a new piston with your cylinders and have them sized, they will run very well and not have the pronblems of sleeves. These srx440 have a very narrow fuel curve and when you get too rich trying to cool the piston with fuel from a steel sleeve they will really be down on power.
To get alot of power from these sleds youll need to port the cylinders, do massive head cutting/rechamber which takes some time due to the offset chamber, and shorten up the intake flange, with aaen wild pipes, 40-44mm carbs(had the best luck with 40mm flatslides) and moving the timing pick up they scream!