bottom line is that he's got a puma with xr2 brakes on it, they might have been fine for an xr2 way back in 1982, but they aren't going to be any good really today, especially on a track regardless of what type of disc or pad he uses as a 238mm disc

if there is a bolt on upgrade that is readily available, as said, you can then find out what sort of pads ill suit your particular application the best