Greek Helmets With Scales

[Feinman]

I just need to find a helmet to use as a basis and get the leather and metal sheets and im ready to start

By "basis" you mean you will cut off the back and faceplates to use with your helmet?
The leather and linen is the only basis you need for the scales; it forms a rigid construction. The Scythian example in the link above, and even those from Koryvantes, all just have a leather, or leather and linen backing. There is no need for a metal helmet under the scales.