hvychev - If you go to Matt's website
www.gmmg.net (I think) and follow the link to the write ups about the car you will know just about all there is to know.
Most of these cars start out a B4C police cars.
In your third paragraph I'm not sure what you are asking but I do KNOW this. When GM finally realized they would not be able to sell all of the 1969 ZL1s they gave most of the remaining cars away to prominant GM racers. The first one of these was car #51 and it was given to Lamar Walden.
Matt did all the cars you mentioned plus a few others like the Carl Black firebirds.
It is my opinion that Matt never intended to put anything but LS6 motors in these cars but when a number of us told him we were pulling the LS6s and having 427s built he decided to offer that option. Again, this is just my opinion.
Also, the original 69 camaro loaded was about $3,500 and the ZL1 option added about the same amount. I believe Fred Gibb was even authorized to return a number of cars which was something GM had never allowed before. I'm sure someone will chime in with the exact numbers.