Recaro S - do I need to buy mounting frames?

This is a heavily edited post - questions have changed:

Bought a pair of 1970 Recaro S including sliders for my 1970 E Coupe – which originally had a driver’s side sport seat that somehow got lost over the years.

I wanted to keep the seats as original as possible and only fix what was needed.

When the seats were taken apart we discovered that they were non-headrest seats - even though very obviously headreasts once were 'fixed' to the seat. The previous owner must have pushed them right into the foam. A shame, really, as I will either have pierced basket weave inserts (if I decide to keep them) - or will have to replace the inserts. Really don't want to do that.

Also, what we at first thought was rust on one of the recliners turned out to be welding spots - and I need new hardware.

So, I have a set of questions and would be extremely grateful for any type of answers:

1. From which year are these seats really?
2. Do I need a special mounting base if I want to put them in my 1970 coupe?
3. Any idea where I can buy one (or a pair) of recliners?

Again: grateful for any answers and advice on how to deal with this now....

Marcus

PS: The car and seats are in a workshop in Europe – I am currently away on business - which means that answers to specific questions might take a while - just as a heads up.