You could pull the hose off and check the od of the pipe it connects to to get the hose id?
Id be inclined to use the correct hose rather than fuel line.
Servo hose is designed to not collapse under constant vacuum. Where as fuel line is designed to carry fuel under pressure and not vacuum. Although to be honest, i cant see why it wouldn't work.
Then just buy some braid sleeving to cover it if thats the look your after.
Rich