273 commando HELP!!!

I rebuilt my 273 2 bbl in auto shop in 1975 or 1976. We weren't allowed to do anything that wasn't "stock." I put in the domed 4 bbl pistons & used a factory 1965 4 bbl manifold & carb and dual point distributor. I added Isky valve springs & a solid lifter .474/284 (IIRC) cam. The teachers suspected what I was doing, so I was told that since there weren't any emission specs for 1964 my engine had to meet 1973 tailpipe specs. One teacher also used to tell us that 273's never idled smooth. My engine idled so smooth you couldn't tell it was running & it passed the 1973 sniffer test. (I might have leaned out the idle mixture to get it to pass....:snakeman: ) After it left shop class it got an Offy manifold, Mallory dual point, Holley 3310 carb, headers, 3.91 gears,......:toothy10: