Well, the owner doesn't know what he has because he says it's "an early Norwood build before they were X coded", when it's actually a Los Angeles built car! It's probably not a Z28 because the tachometer has the wrong red line. This one looks to be 5500, which would have been used on a big block (which it isn't), but variations in tachometer red lines versus engine have been observed, so it may be an L48 since they've been seen with 5.5k red lines. Especially if the 12 bolt axle is original to the car. I don't think there are any Z28's in the database with the 5.5k tach though.
If you're interested in the car, you need to get the numbers on the axle and the transmission and post them here. You'll also need to get the VIN.
Ed