All three species go through a color change as they grow, but Borneo short-tails (P. breitensteini) change the least.

If you're trying to pick out nice reds, seeing pictures of the parents really helps, as selective breeding goes a long way with these snakes.

Most adult bloods & short-tails in captivity are within the 4' - 5' range, very manageable snakes. If you're worried about size, you could go with an orange-headed/yellow-headed Sumatran short-tail (P. curtus), as they're the smaller race of these snakes. Keep in mind that they can get fairly big & heavy as well...I've seen some very big yellow-headed female curtus.

Just for comparison, my biggest short-tailed python at this time is a 6'+, 28-lb, 13-year-old female. These snakes need age to really attain massive size. A 6' blood/STP is a VERY impressive snake.

$.02...

K~