Done 30 miles on the rebuilt hub, all good, seems like axle HSA 370 is a good replacement for HSA 108.
The HSX 120 internals I think were binding on the end of the hub preventing it easily rolling backwards, still to get to the bottom of it but think the new assembly is a fraction (approx 0.5mm) longer than the original internals. Although it kind of worked I wouldn't recommend putting them into an 80's AB hub. Good having everything back together again.