Hi Jianyu,
Welcome to ACES Central 
When using ACES as colormanagement in Nuke the working space is set to linear/ACEScg. Any footage that comes in needs to have it’s proper input device transform selected. The ACES config will automatically convert from that to linear/ACEScg, no manual steps required. For raw files you will have to match what you’ve selected in the metadata to decode to however. I downloaded Helium sample footage and came to this setup.
If you want to perform that step manually you could check ‘raw data’ so OCIO doesn’t auto convert it and then use an OCIOColorSpace node to go from whatever you’ve set the R3D file to, to ACEScg.
(To double check that the footage is coming in as Log3G10/RWG you can set your viewer to Raw temporarily.)
For more modern RED camera’s it’s a bit easier because they’re set to REDLog3G10/RWG by default I think with the IPP2 system.
Don’t have much experience in that regard but from what I understood is that the Nuke default config only has transfer function conversions so your approach sounds correct.
Hope that helps!