If you use BaT make sure the car is ready.
RSRs do well if they are completed with a high level of detail and finish. I would review the RSR builds that Dave K built here on Pelican (sold for $200,000+) set your expectation accordingly.
https://bringatrailer.com/listing/1982-porsche-911sc-4-2/
https://bringatrailer.com/listing/1984-porsche-9111973-rsr-recreation/
https://bringatrailer.com/search/porsche+rsr/
My read on BaT is do your homework and again have the car prepared. Write an Ad with all build details, plenty of documentation, pictures, videos and clarity. 911R has sold quite a few hot rods above market I would use his ads as a how to guide.
You might need to invest a couple of bucks but the BaT marketplace rewards with well sold cars...…..