The GSO Tilt ring, a well collimated generic laser collimator and the OCAL electronic collimator did a good job on my GSO 8 RC, with a final (and easy) conventional manual fine-tweak star check, the only bit you can't do on your kitchen table after lunch.
The OCAL is a good investment, will do Newts, SCT's and RC's. Pay no regard to the Chicken Littles, it works well. Google is your friend.
OCAL have a Youtube video for doing the RC:
https://tinyl.io/6lpR, but you should first use the laser to check and adjust focusser tilt before using the OCAL to do secondary and primary adjustments. Rinse and repeat a few times and you should get a good final result before the final star test, which will just be a secondary mirror screws tweak if needed.
Small hint, put your phone camera in the mouth of the RC so you can easily see the secondary mirror donut (reflection on the primary mirror) when adjusting for tilt.
Not an overly cheap set of tools, but worth it if you want to make the GSO RC really hum.