Myko2
Have a look at
Wade Cams They have a nice selection of cams for us.
Another one is
Tighe camsWades 112 profile looks to be a GX replacement, while the 104 profile should also work quite well.
The Tighe 102 profile looks to be their version of the GX replacement cam, while the 113 is described as "mild road" & the 154 is the 'fast road" version. All of these cams will give their best with better carbs & exhaust, but do not need dual webbers.
At this time i look like using the Wade 104 in my "improved" GX, while Tighe advertise that they can supply cams ground on new blanks. The Wade 104 has reasonably modest specs, but a healthy amount of lift at the valve, so it will breathe deeply at all road speeds without much rump rump [if any]
Look at the specs for both, then make an informed choice.
Remember that your US dollar buys more in Australia.