That is real nice!
If I had to guess, it probably has some correct DZ 302 parts like the block and intake manifold. The blocks can be picked up on EBay like this one:
http://www.ebay.com/itm/DZ-302-Block...item45ff2120a6
I saw postings on a few sites where the car is a numbers matching car where Nelson rebuilt the original DZ 302 to stock specs. Then they pulled out the drivetrain and put it into storage. Then Nelson put in the disguised 302/427.