John--Sorry to say that it is GONE. Richard Brandi, writing for the San Francisco Encyclopedia chronicles its fate:
"...they were not successful in keeping the original West Portal tunnel entrance, an imposing Beaux Art landmark that was demolished in 1976 to build the current West Portal MUNI Metro station. The Ford administration found the facade eligible as a National Historic Place but local West Portal merchants thought it was an eyesore. The new station wound up costing $8.5 million, more than twice the entire amount of the 2 1/4 mile tunnel in 1918."
I thought that there was a pic of the demolition on this site, but I couldn't find it...nothing on the SF Public Library site, either.