Quick question about proportions in playermodels

What is the best way to reproportion the valvebiped skeleton for use in a model with slightly different proportions? e.g. if a character has shorter arms than the model I imported the reference from, what is the best way to change that? Currently, I’ve been moving bones but keeping the orientation the same, and this partially works. However, it seems to stretch out in areas when the models aren’t of the same proportions. I’m using Blender.

Thanks in advance,
Grey