For a race gun just go JP LMOS with a 18" JP barrel with an adjustable gas block.
What matches do you plan on shooting? Even in Socal the longest shot is 300 yards, IIRC. Most up here matches are up close and personal, so a 14.5" would even work.
Both of your choices are go barrels.
"SS, you beat me to the Post button. I was thinking for too long."