Screen Security Door handle and latch broken and odd sizing

The handle is broken and latch mechanism is missing on screen security door of home I purchased. I tried to find a complete replacement set, but I can't find one that matches the screw holes as they are 7.5" and the ones I've found are either 6.5" or 7 15/16's" and stores say this unit is old and very hard to find. I'm hoping because of that, maybe I can just purchase the replacement parts I need. Can you help me? Just FYI, the deadbolt mechanism works just fine so only need handles and latch mechanism that will fit this unit.