Alot of people have been asking about how large certain snakes will get and there have been many different answer being given so I thought i would check out The Guinness World Book Records. Heres what I found out:
HEAVIEST: The Heaviest living snake is a Burmese Python weighing 182.76 kg (403 lb.) It is 21 years old, 8.23-m (27 ft) long, and has a girth of 71.12 cm (28 in) Known as "Baby", she lives at the Serpent Safari Park in Gurnee, Illinois, USA.
LONGEST: The reticulated python (Python reticulates) of southeast Asia, Indonesia, and the Philippines regularly exceeds 6.25 m (20 ft 6 in). The record length is 10 m (32 ft 9.5 in), for a specimen shot in Celebes, Indonesia, in 1912.
OLDEST:The greatest age reliably recorded for a snake is 40 years, 3 months, and 14 days for a male common boa (Boa constrictor) named Popeye, who died at Philadelphia Zoo, Pennsylvania, USA, on April 15, 1977.
Pretty sure that these records should be accurate considering the source i got them from. So hope that helps answer any questions