Yes, you can register a 1976 Chevy Suburban in California as long as it passes the smog check. It must not have any of it's emission systems tampered with and it must pass the exhaust emissions portion of the smog inspection. To be sure that it will pass the emissions test part of the smog inspection you may ask the seller to perform an engine exhaust emission test in Idaho and compare the test results with California's emission test cutscores, to which we provide a link below. The Suburban's emissions (HC, CO, and NOx) must fall below the maximum limits set by the California Air Resources Board.
https://www.bar.ca.gov/pubwebquery/cutpoints/showmake.aspx
