Upper_Krust
Legend
Raditz can more or less tank moon-buster shots, and no sell said moon-busters.
...looking into it a bit more...
Piccolo's Special Beam Cannon - which killed Raditz was (at that point) akin to a low yield nuke. Splitting the difference (between 1 KT and 1 MT) lets say 30 Kilotons = 735 damage by my rules.
He is hypersonic (or superluminal if you go by certain dubs, but that's a stretch) and is considered a supreme weakling in his setting.
I have rules for that in the book. If he was Hypersonic he would be constantly under the mechanical benefits of a double haste (on top of the movement speed increase).
Even then however, I cannot give him a bigger number than yours since he has no resistance to mind effects or spells in general(and 5e has no infinitely scaling 'saves' due to sheer HD) so... yeah. That's a universal argument against most DBZ characters.
My revised estimate would be to put Raditz close to CR 24/Divine Rank 3. With Goku and Piccolo (at that time) in around CR 16-20 Divine Ranks 1-2.
The Special Beam Cannon can potentially double its power every round it is 'powered up' to a potential maximum of x3, lets say.