Add-on Newsfeed adjustment

In Xenforo under Applications > Register Feeds you can add a newsfeed to pull information from a source to the forum.

Currently there is the option to post everything or just a title with a Link

Example {title} or {content}

We want to encourage people to visit these blogs but if we post the entire content of the blog there will be no reason for them to visit the blog.

We are wondering if a modification or add-on could be created where we could tell the XenForo feeder to import the first 50 words or an image and then the first 50 words.

I have been told the change can be made in library/XenForo/Model/Feed.php however i don't have the required skill to make the adjustment.