I have a "real" '69 Z28 with a 302 , I can't see the vin # on the block(engine is in the car), The date codes are close enough that it could be the engine that came with the car.The trans and rear axle are not original, would it be worth the work to pull the engine out to see the vin better, or would it not add that much to the value of the car since the rest of the drive train is not original?

You should be able to get the car up on ramps or jackstands and see the partial VIN down by the oil filter. No need to pull the motor. Give us more info on the dates of the stuff and if you can post up a picture of the engine stamping it will help determine possible originality.

Jeff, I posted a thread on Tag team with pictures, and alto of guy's looked at it including Kurt S., some thought they could see something and some didn't. So if having a 302 with a vin # instead of not would make the car that much more valuable then I might decide to pull the engine. If it's not going to make that much diference then I will wait untill the engine need's rebuilt again in 20 years.

to me, if the motor doesn't match then it's not that big of a deal about the tranny or rear end. I'm sure others may feel differently. I have the original tranny and rear-end sitting in the garage because my '68 project did't have original motor. But, I'd DEFINATLY want to know if it's the original motor! especially a 302.

If the engine assembly date is within two weeks of the car it could be the original. Since the rest of the drive train is long gone, it's more than likely your original motor is too. It's been almost 40 yrs!
Drive it and pull the motor later.