Hello @eugene,

Does RSS help you to meet your needs?

http://b2evolution.net/man/advanced-topics/how-to/use-rss

Also look at: http://b2evolution.net/man/advanced-topics/how-to/make-a-site-map

And to answer your primary question: the "Contents" block is a widget and you can change the maximum number of items that it displays:
http://b2evolution.net/man/back-office-reference/managing-collections/widget-settings/widgets/simple-post-list-widget

Excellent - extending the number of lines the widget displays worked well. I can copy/paste this into a page to be used as an index now. Many thanks.