If it’s a dark colored chassis, cracks will be a lot harder to see. Run your hand down tubes near all joints to feel for any cracks and inspect with a light.
Check the wiring everywhere for hack jobs and ghetto repairs. Hell, any evidence of “dune fixes” still on the car are a huge red flag.
Jack the car up, wiggle tires top/bottom, left/right for play, and rotate the tires for gritchiness. The rear tires should rotate freely by hand with no hard spots at full droop.
Bore scope would be useful to see exactly how long it’s been since that “fresh rebuild”. You can also check the R&P for chips.