if your original hdd is smaller than 240GB (or, isn't full and you can shrink your partition down using gparted or something), you can use macrium reflect to copy the image from one drive to another...i agree with cdabc123 -- 2 hours is probably reasonable, assuming your essential files are backed up in case something goes wrong.
i went from a 64GB SSD to a 128GB one using this guide:
http://www.howtogeek.com/199068/how-to-upgrade-your-existing-hard-drive-in-under-an-hour/
shrinking your partition down first, if necessary, may take a while.