35 psi for the car is probably due to the fact it has Hydraulic lifters. The hydraulic blocks have have larger oil passages and divert more oil to the cam and lifter assembly. The trucks would have mechanical lifters. My service manual shows the later 58-62 engines only running at 35 psi also. All the 58-62 blocks were drilled for hydraulic lifters regardless if it was a hydraulic of mechanical application.
