You judge a barbecue joint by its smoked meat. And the best comes from a real pit. The old cinder-block pit in Thelma's on Live Oak ought to be declared a historic landmark. The design was brought to Houston by the legendary Joe Burney of Beaumont back in the '20s. Harry Green, and other Houston barbecue legends who learned the trade from Burney, built pits like this in several Third Ward locations. When Harlon's bought Green's old location on Almeda this past summer, the first thing they did was to take a sledgehammer to the cinder-block barbecue pit. In its place, they installed a stainless-steel contraption. Drexler's on Dowling did the same thing a couple of years ago. The new stainless-steel barbecue ovens, with their gas and electric heating and automatic operation, are convenient for restaurant owners, but the virtual barbecue they produce doesn't measure up to the old-fashioned pit 'cue at honest-to-God joints like Thelma's.