Shaved mine .040" (360 w/ K8600, Crane springs-retainers, stock-length pushrods, stock bridged rockers, Summit lifters). I knew that mine had not been shaved before, and a local race shop agreed that this amount was safe. I cc'd the chambers & measured v/p clearances w/ clay, but that was years ago and I've lost the numbers.
360, .030-over, K8600 cam, Crane springs, ported heads, Edelbrock Performer, G.M. TBI, TFI, 3" exhaust,
T-18a/208, D44/AMC 20 w/ limited slip in both, 3.73s, 33s, BDS 4" springs, Rancho 9000 shocks, etc., etc.