I've written the paper backup on notes by hand (I don't own a printer) and haven't noted the version of the wallet. It this a necessity?
So far, 1.35 is the only wallet version that has ever existed. And 2.0 will be the next, and hopefully final one. I expect that there will be a drop-down list to select the version -- given that paper backup information will look dramatically different for each version, it should be clear which version you used, just by the entry fields that show up when you select 1.35.