You can do this in 3 ways: 1. just add site: before every url you need to crawl and put it into a harvester. This will find all the urls that are indexed in the search engine.
2. Use the link extractor, set it to scrape internal links. Insert the 600+ urls and it will find an x number of urls of these sites. Now insert the x number of urls you got and repeat until you get all the internal urls.
3. using the sitemap scraper which is also a plugin in scrapebox
With this three ways you can find all the links you need. happy scraping