so im building several new sites to replace my old ones that were penalized by penguin. Im thinking to port all my content to save some money for content generation. What Im doing atm is blocking Google spiders for my old sites in robots.txt, submit "URL removal" in google webmaster tools to delete those old sites in Google index, and later (after I port my content) i will simply delete the files in the old sites. Would it be enough to avoid duplicate content issue considering Google (by then) shouldn't have my old sites listed in their search engine anymore? I don't do 301 redirect for now because I was thinking 301 redirect would "pass" the link juice from my old sites' backlinks and that would be bad for my new sites, isnt it? What do you think? Should I do 301 redirect from my old sites/domains to my newer ones or I should just delete them after porting my content?