With a california car, you're probably not getting rust, so thats good
The main thing is the clutch slave cylinder, but I don't think there's a way to detect if it's gone until . . . it's gone. I would ask for sure if it's been replaced, but really the only surefire protection is an upgraded one.
Look for any wierd tire wear to indicate alignment (or if that dude's been doing burnouts)
Leaks
Blown bushings
any replaced panels inside/out to indicate modification and/or repair due to unreported accidents
I'm sure there's more but thats off the top of my head
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