Hair sporran question

[artificer]

As others have noted, the length of hair is somewhat determined by the type of hair as well as the time the sporran was made and the style of the day.

In the Victorian Era it was quite common for sporrans (frequently goat or possibly Highland cow) to come WELL past the selvedge edge of the kilt.
Contemporary (horse) hair sporrans tend to end right at or just above selvedge, and goat hair sporrans, due to the shorter length of the hair, tend to be a bit shorter than that.

I don't think I'd probably do a horsehair sporran that is much shorter than standard, they tend to 'brush out' like a broom head if there isn't enough length and weight to keep them in order.
As Bluescelt mentioned, you can get a longer goat/Highland cow look by extending the bag (although realistically you probably won't want a contemporary construction (with two hard panels and a gusset between), as the hard panels would knock against the thighs while you're walking.

ith: