My house has a 3 season sunroom which means there is only a storm door. I found a used slab entry door to install (for security as well as a step towards climate control). I bought the door off craigslist and the measurement for height wasn't quite what the door really is. My installed storm door is 80" and the new (used) entry door is 79 1/4". Since there is a storm door installed the frame exists.

What are my options for using the shorter entry door? Can this be done?