I seem to recall reading in the Straight Dope that altitude is good for an extra 40' at the point in CF at Coors. Presumably that would assume all kinds of things like equal pitch speed, bat speed, trajectory, etc etc. But with 20% less atmospheric pressure, 10% more distance seems more-or-less reasonable. Anyways, Morse's hit looked like it would have come straight down at the center fielder at home.