Same method with REST And AsyncAPI

I have an API built using OpenAPI that has a few endpoints that render graphics and can take up to 30 seconds to complete. I am looking for recommendations on the best way to expose those specific endpoints as AsyncAPI without adding too much overhead in managing the two specifications.

Any suggestions or experience with a similar setup would be greatly appreciated.

Note that I'm not specifically set on AsyncAPI, so other recommendations are welcome too.

Thanks!