Resto of '78 Spider

Greetings:
I'm looking to restore my 1978 124 Spider. Bought it in new in '78,
put close to 200K on it, refreshed the engine about 40K ago, but for
the past 4 years, it has sat under a cover, untouched.
Last time she ran, she was smooth, and in need of very little
mechanically, but in dire need of an interior overhaul, and some body
work and a full paint job. My first order of business, (after a
thorough going over by my tech for leaks, seals, etc., is to replace
both front seats. The WHOLE seats, mechanisms and all, as they are
pretty shot. Problem is, I can only find re-upholstering material, but
no actual seat frames (runners, tracks, etc.). Any idea where I might
begin to look?
Also, eventually I want to dispose of all the smog restrictions (will
be legally registered in a Ca. county which does not require it), and
was wondering the best way to go in that regard. Headers, carbs and
maybe a new intake? I've already switched over from points to elec.
ignition.

Thanks in advance for any insight.