If you can have the gap at the bottom, you could attach a weather seal to give you the rest on one side. If it looks funny at the front, attach a metal piece (or another weather strip. The other option might be to special order, but you will probably have to pay twice as much, and there are no returns or exchanges.

Add a 1" thick piece of hard wood(like oak, ash, or maple to the inside top of the door opening---making the height 80 inches.

The trim on the storm will cover that wood piece. Just predrill pilot holes for the screws used in that top piece.

handymac, I thought about adding a strip of wood, but wasn't sure. Not that I'll be doing the installation but if the person doing it doesn't think of adding the piece I'll suggest it. thanks.

drywall, you got that right. A couple years ago I was quoted a $700 estimate for a custom door in the style and type I wanted. ugh.