Actually there's a guy rebuilding an R/C model of the Curtiss O-52. From the photos I've seen on his build thread, the model looks very realistic & built to scale. I believe this model was originally built from a set of plans.
It was agreed among fellow modelers including the builder, that the main challenge will be having a retracting gear. From what is being said, the gear is not the same size as those commercially available for use on the popular Grumman Wildcat R/C kits often seen. This means he'll have to have it customized, if he wants scale retracts & they can be very pricey. So he still has a ways to go before it's considered complete let alone airworthy.
I used the term: "rebuilding" because he obtained it from another fellow modeler who crashed it. How it was damaged was not presented in the build thread or how much scale detailing went into the model is also not known.
However, unusual or rare aircraft are normally not produced in kit form (regardless of scale, plastic, mixed media, or wood). Markets just doesn't justify the enormous costs involved in laying out the molds & producing even a limited run kit.
I'm sure everyone on this site could come up with several aircraft that have not been kitted. Just the way market forces flow. I could name a few I'd personally would love to see in kits.