Upgrading fat PS3 with 4.46 CFW to current CFW?

Hi!
I've mostly forgotten my PS3 last couple of years, but would like to get some use out of it now.
I completely forgot what CFW I have, besides that it's 4.46.

What would be the recommended steps and CFW?
Is Rebug 4.84.2 REX a sensible choice?

Thanks!