I bought my little ones from Reptile Basics.
http://www.reptilebasics.com/feeding...ng-needle-set/
I recall seeing larger ones for feeding squirrels and birds. Here are some that are a little larger than the RB ones:
https://www.squirrelsandmore.com/pro...feeding-needle
I imagine a 2500g boa needs at least 18 inches to reach the stomach?