Actually 6 an is 3/8". The number the hose is called, i.e. 4an, 6an, 8an, etc.. is the amount of 1/16ths. In other words 4an = 4/16 (1/4)", 6an = 6/16 (3/8)", 8an = 8/16 (1/2)".
Hydraulic fittings are very easy to work with and you can make them look nice and neat. Sounds like a good plan wjaholic.