First, let me suggest that by upgrading from an older version of PlatformPro to PageLines Framework, you'll find many things are different. Among them is that there's no need to modify core files. In fact, doing so in Framework will likely break your site, not to mention violating your license.
In Framework, if you go to the page you're planning to add your slider to, you'll now see PageLines Meta Settings > Features, where you may set the height of the slides that appear on that specific page. This gives you greater control, allowing you to have different size sliders on individual pages.
If you prefer a more global approach (all slides the exact same height throughout the site), you can go to Dashboard > PageLines > Page Options > Site Defaults > Features, where you can set up slider defaults for the entire site.
Features now have the option of static or aspect-ratio sizing. Static would be, for example, 340px high. Aspect ratio would be a scaled down image. So if the image is 1000px by 500px high and the aspect ratio is set to display a specific ratio, you might see that image as 500px by 250px, scaled down. The one issue with this is that you must make sure your original slides are all the same size so that in scaling, they'll appear the same.
The new Feature Slider has many more options than before as well. I'd suggest reading this: http://support.pagel...tions/features/