Belt Grinder!!!!!!!!
I worked in Pulp/Paper mills for many years, we had big rubber covered press rolls up to 240 inches face width and 44 inches diameter. Standard machine to grind the rolls was a big Ferral Roll Grinder using a Norton Belt grinder with 4 inch wide belt. Started with a 36 grit then to an 80. Sometimes went to 120 depending on the roll covering material and where the roll was used in the paper machine. Water cooled to flush the rubber off the belt. (Belts are waterproof). Sorry, don't have photos.
However, a smaller belt grinder is really easy to build, all you need is a contact wheel and a crowned idler wheel. If you are into grinding rubber on a regular basis, I recommend building one.
Here is the basic belt grinder, just think vertically, build it to fit your compound rest and have the contact wheel on center with the roll you are grinding. Be sure to use a reversible motor, variable speed. This one uses 2-1/2 inch wide Norton belts, 60 inches long. The mount for the crowned idler wheel is spring loaded and also has a pivot so the idler may be swung for adjusting belt tracking.
Below is a tiny one for gun barrel work. It has a DC motor, variable speed controller. Build one similar but scaled up for 1 inch or 2 inch wide belts. The little wheels are rubber covered contact wheels. The motor wheel is flanged. The sliding arm is spring loaded to tension the belt.
The belt grinder cuts 10 times faster than a wheel and does not clog or burn, you will love it. Talk to your Norton Rep, they are the experts in belt grinding rolls.
You can do this too, called "slack belt grinding", for a final finish. Note the vacuum hose. Belt is running in reverse, against the direction of rotation of the barrel, this plumes the grinding dust up and the vacuum grabs all of it. Use the contact wheel to get the rubber roll round first, then finish with the slack belt if needed. Experiment!