I always use 10K! 
The adjustment for leds with different forward voltages is small, so I don't worry about it. The ISET resistor sets the peak current, and with 64 leds, the average current will be one eighth of that. Most leds will take 4 or 5 times their max continuous current as long as the duty cycle is 1 in 10 or less and the pulses are short (eg. <1ms), so I figure 2 times the max continuous current with a 1 in 8 duty cycle is probably ok.
I did have some trouble with leds blowing when using '7219 like this but they were dirt cheap leds off ebay and I don't think the quality was great. With better quality leds I've had no problems.
Paul