I am really visual, but it was said that the 10 minute blocks are 10". Going from this measurement, if you want your pics the same size as the blocks--you could add 3" border to the 5" side, and 2" to the 7" side and you would have a 10" block.
I haven't made this 10 minute block, so I am not sure how to make one that is 5" x 7".
I hope this helps, it is kind of hard for me when I can't see what I am calculating. I admit to being a very visual person.
If this isn't what you are doing if you want to pm me I will try to help you calculate it.