Here's an alternative perspective. I'm having the interior and trunk of my signal-red '71 280SL restored and enhanced. No structural changes, but all surface materials are being upgraded. For example, we are getting brand new MB carpet in flat roll and then forming it to the interior and trunk (spare removed). Far fewer seams than the original interior carpet this way. All MB tex materials are being replaced with leather of the quality used in Gulf Stream and Falcon jets. Everything is being covered in this leather. Seat heaters, active seat ventilation, auto-dimming rear-view mirror, etc., etc. are being added. The Frigiking unit will maintain its original look, but everything inside is new and will be pumping out over double the normal air volume, plus it has been piped so that A/C also comes out the chrome vents on each side of the dash.
I'm not advocating such enhancements, but it will make the car much more comfortable and pleasant for my wife. And since only surface materials are being upgraded it could all be easily returned to standard W113 materials at any time should the mood strike.
Tom in Boise
P.S. We looked for the finest quality carpet material we could find. Aviation stuff, that used in Rolls, Bentley, Ferrari, etc. But the new MB carpet seems the best to us.