Unknown Track Bike: Mercian Super Vigorelli / Gazelle Champion Mondial

A few weeks ago I went to take a look at this old track frame, not sure what exactly was on offer as nether myself or the dude trying to get rid of it knew exactly what it was.

• Frame + fork number: '1875'
  
• Campagnolo faintly stamped on the rear dropouts
  
• Nervex stamped on BB shell lug plus the other lugs all look very Nervexy
  
• Unfortunately the fork crown was drilled for a front brake buy the previous owner and it's a bit messy.
  
  

Kinda fell for it since it was in my size, the details were nice and felt like it needed a more loving home. Anyway, the plan is now to completely restore it with a nice paint job and fresh decals...but what is it???

Is it a Gazelle Champion Mondial Pista?

• decals say it is
  
• but I've never seen one with the seat say / seat tube wrap around detail like on this frame
  
• and never seen a gaz with Nervex lugs?
  
  

Or is it a Mercian Super Vigorelli?

• the seat tube / seat stay wrap around looks similar, plus I have seen Mercian's with Nervex lugs...
  
  

Or is it something completely different?
Would massively appreciate if anyone can share their knowledge or opinion!

Also I plan to eventually build it up, so please shout out any component suggestions