Did you made the original pages with the 800 something Pixel? If you do, then I recommend you to draw on a bigger pixels, like twice of the original or more. If you do, the time you cut and resize it to be the second version, they won't Get blurred.
(is this what you're asking for tho? XD)
The maximum resolution tapas allowed is 940x4000 pixels, so maybe try to made it doable from the width number and resize it to it the upload.