trouble finding an inside handle that fits

by duke
(glendale heights, il, usa)

the outside handle has a key lock in the center, the screw holes are 4 15/16. Height is about 6.5. I am having trouble finding an inside handle that fits the 4 15/16 screw hole that will also lock from the inside. I am afraid to order a handle that might not work. do you think you know what kind of handle this is? or can you recommend me one that works?