Sorry for the damage to such a sharp looking Z. I've aggressively driven the Angeles Crest area quite abit in my Z4 coupe and it is fun-(albeit unforgiving)...even though some areas were burned out so bad.
The fact that your seat looks tweaked requires more inspection.....good chance it is just a tweaked seat-back or rail.
I have restored over 30 S30's over the years and I can say for sure....although your chassis can be straightened and repaired....I would personally find a straight unmolested body and research good shops to get it stripped,sandblasted,etch primed and ready to swap over all your already restored bits. Also a great time to dial in all the other parts that were needed prior to the damage.
Looking forward to a great turn-out for you !