About 7-8 inches I think, although I don't actually measure them.
Just an idea, Why don't you make the hooklink twice as long and tie a loop at the opposite end to the hook. Thread the loop through the eye of your swivel, and pull the loop down towards the hook, so now the hooklink is doubled up, push the hook through the loop and pull down an inch or so,tie a piece of pva round both bits of hooklink and tie another pice of pva by the swivel.
When the pva dissolve's the loop is now free to travel up the hooklink until it hits the swivel, the hooklink might just be enough to make the fish panic and bolt giving you the best of both a running rig as well as a bolt rig.
Just an idea i used many years ago,
Can't really visualise that sitting on the train, but will try to recreate it in the shed tomorrow, see how it hangs. Cheers