BBCs are very tempermental regarding valve train. We've had PROPERLY prepared high revvers touch the pistons with all 8 exhaust valves. I always give them .120" on the exhaust if going over 7,000. It's a good "habit" to keep, in any case. The tiny loss of compression is far offset by the less perilous position of the valve.
Listen good!! Many BBC's become history because of this problem. I always used the .100" on the exhaust but not on a BBC, they will at least clean the carbon off the piston pad on the exhaust side..