Hi,
it looks to be a mid to late 80s Campag C-Record rear hub, it should have an OLN measurement (rear spacing) of 126mm, according to the velobase website.
The alloy part on the non-drive side is the dust cover for the bearing assembly, it's removable for adjusting the bearings with an expensive proprietary tool (see ebay), or more carefully with a wide flat-bladed screwdriver used slowly to lever it away from the body.
It looks to be an example that is threaded for freewheels, once the freewheel is removed there should be some spacers that can be removed from the drive side axle assembly allowing you to bring the spacing back to the 126mm you require (although unlikely, it may be possible that there is also a spacer(s) on the non-drive side, these would be obvious once the dust cover is removed).
Once you have reduced the rear spacing you may need to slightly re-centre the bearing races so that the amount of threaded axle exposed is equal on both sides. It is worth checking this new axle measurement to make sure it will still clamp correctly in the rear dropouts, although effectively adding 1.5mm to each side should not be a problem if it's still the original axle.
Hope this helps.
Cheers Matt