Coming a bit late to this thread, but another way to do it is to completely re-typeset your scroll for different frame rates (24, 25) and aspect ratios (scope, 16:9 full height, 4:3).
After killing myself making many very painful end credits scrolls, I created software that does just that: https://endcrawl.com
I agree with Dave that a lot of scrolling end credits, even on big-budget films, look rough. This is partially a workflow issue. If you just have one master output of the scroll, scaling and re-timing will introduce all sorts of nasty artifacts — shimmering, stuttering, etc.
One thing you can do with Endcrawl is just keep rendering until you’re done. Under the current private beta, you get unlimited renders, so you can keep versioning and get tweaked outputs for all of your derivatives.