perch sizing

I’m trying to figure out how to replace the dowel perch that came with my green cheek conures cage, with a natural one. Any ideas or suggestions? I included pictures of the cage I bought for reference of the length and size.

I'm finishing up my preparations to bring Maui (WBC) home but I'm getting stuck on deciding on appropriately sized perches. I have a good roosting perch (2.5 cm diameter), some sisal rope perches, a manu mineral perch, and a flat corner shelf. Unfortunately I am having a hard time finding a...