Can anyone ID a 275 horse 273?

I found this statement on an allpar link:

The first LA was the 273, with a two barrel carb, and 180 hp (gross). By 1965, a four-barrel carb and high performance cam were available to push that to 235 hp; and, in 1966, a limited edition 273 with a 700 cfm carb and .500" lift cam put out 275 hp (gross).