That blade for a 9" grinder looks like an accident waiting to happen to me. Can you imagine the kickback off it if it jammed! Crazy!
I was going to say about the Arbortech, but I can see someone already did. you can get them from Axminster. They do a guard for them as well. Never used one, but they seem safe enough if used properly.
Nine times out of ten, and again as already suggested, for a "one off" job a hand saw and a bit of elbow grease are going to be as fast as mucking about trying to get a power tool to do the job.