Here are my OC settings for 2140, pretty much the same as you suggest:
(and no, my warranty didn't void, if anyone is curious)
Keep up the good work!
I have two RPi4 - 4Gbs. The first I got to 2147, but after about an hour it would finally crash.
I have built a web-based overclocking tool for several Raspberry Pi models, including Pi 4 and Pi 400. It suggests medium and maximum overclocking settings to you, as a good starting point - to take the guesswork out of the initial step!
Possibly you'll find it useful:
I'm also including information about how to test whether an overclock is stable on the tool's page.