I bought both of these cars and after 48 hours of seat time in my truck over the last week, they both reside in my garage!! When I went to look at the cars, I couldn't get a good look at the oil filter area on the Z/28 as the car was sitting in the trailer where it had been for the last eight years. I did look at the date stamp on one of the heads through the oil filler hole and the date stamp was E290 which I believe is May 29, 1970. I also found a stamp on the transmission that I think was P7A11 which would be a 1967 transmission. So, at first glance, it looks like the Z/28 has all the right parts, but probably not the original parts for that car.
I need to start on the 68 to get it ready for my wife to drive next summer so I'll be spending a lot of time searching this site looking for vendors and information.