You mean longest and/or heaviest actually recorded, or alive?
I believe the longest ever recorded was a retic that was killed circa 1912...it was measured at just under 33 ft long. There have been many rumors of larger green anacondas, but apparently the documentation left something to be desired because they are not generally accepted. Likewise, there are frequent reports of record length retics being captured/displayed throughout Asia/Indonesia...unfortunately, they don't quite "measure up" to the hype.
A record length green anaconda would certainly take the heavyweight crown, but (last I knew) the heaviest living snake was a 400+ lb burmese python