Converting existing door handle to keyed on Sliding Door

Hello! I don't believe the 82-086is the best option for you in this case. The thumb lever on this handle set is fixed in the bottom position and cannot be adjusted in any way. Meanwhile, yours appears to be in the center position.

With that in mind I recommend the 82-030. This works the same way as the 82-086 but has an adjustable thumb lever, allowing it to work in any position.

I also recommend double checking your hole spacing before you buy anything. I don't think 3-1/2" is accurate, it should be 3-15/16". That's more common for doors like this.

Sure, if you needed an exterior key lock then you can use our 82-310 (sold separately). This is fully compatible with the 82-030.

Both the 82-030 and 82-310 are compatible with your mortise lock. As long as it's still in good condition then you can reuse it.