Where can I get a blueprint of the Chevrolet C5R Production racing
engine particularly the block?

Raymond, 

As far as I know, the C5R is still racing, and its engine blueprint
might therefore be an industrial secret.

BUT, I know that some of the companies sell their blueprints to the
public, when the specialities of the race engine are less important
for competition.

Chevrolet sells the C5R engine block to the public. I can wait until I
have the block and measure it myself but I would rather not wait.
Since anyone can do the measurements the data should not be
confidential.