What kind of backwood crap is this? Sure a 318 can be a performance engine - ANY engine can be a performance engine if you build it right. I would consider anything at 1hp/CI or better a performance engine and in stock form a 340 ain't quite there but some people still consider it to be a performance motor. Of course a stock 318 is pretty average but that can be fixed fairly easily. Not everyone has 340s or 360s hanging around to build up and if you had to go out and buy a 340 or 360 to rebuild, why not go straight to a big block?