Tulip chair question  

I've just accepted a comission to restore a set of tulip chairs and two matching tables.
The bases are NOTcast aluminium, but rather spun steel, they do not have the radial lines that i see in the photos I have come across.
It's not a marble top, just plam (best match I could find was Formica Dover white post form thickness). Got the matching epoxy paint for edges treatment on order. Bases are off to the powder coater (per architect/designer owners request).
I haven't figured out the rehabbing of the fibreglass shells yetbut I'll get there.
These were purchased by my clients some 50 years ago, from a reputable store, and they admit that they could have been reproductions.
But from all the myriad of photos I've seen of real and repros, none of them show a v-shape in the back of the chairs. Has anyone else seem this? Perhaps a name/supplier reference?
And the replacement of the floor protection moulding? any sources anyone could think of would be appreciated.

The only tag I found was a "made in Canada" sticky.
If anyone has a bona fide original, I would like to see the details of the fibreglass shell attachment to the base. I think pop-rivets, but aluminium or Stainless steel to replace? The chairs have seem a hack repair by a welder, so they have been to the tinkers shop before.
Any pointers/observations/comments would be much appreciated.
Even if they are repros, it would be worthwhile to my Karma to restore them as close as possible to the original.
Can anyone out there help here
Eric in Calgary