Mate, as you know shooting groups off a bench & real life hunting are 2 very diff things...just start with the 222, and know your hold over out to what ever range you can shoot them too, & have the 243 on the back seat.
The 243 is a bit too loud for a roo gun, but you could use it if youre not comfortable with the 222, &/or on the longer range ones when the wind blows up a bit.
If youre going to be shooting in the wind, know what your wind reading limits are too...
Id suggest just smack a good few at normal modest ranges with the 222 (maybe out to 130-140...or stay at 100-120 max if you prefer) and that will give you some confidence...try putting the bullet in their brains rather than just aiming for centre of head mass...& remember to stay within your known range ability.
I rekon a good shooter is someone who knows their ability & has the kahoonas to not take a shot if he is iffy about it--irrelevant of whether thats 80 metres or 280 metres
--from a shooters perspective, "having a crack" at a 220 metre shot & fluking a hit is just as bad a shooting as blowing the snout off one & having it get away ...so if you havnt shot roo's head sized targets & landed most or all shots in a couple of inches-ish on paper at 200, dont try it in the field--remember your groups off a bench will be bigger in real life in the field...
If you have a range finder, carry that with you & range as many as you can to get a feel it...& also range the ones that youre not sure of...
Roos heads are pretty big target, but they vary quite a lot in size (young to big buck) so depending on the lay of the land & your perspective, sometimes under a light a big roo's head at 180 can look like a small to medium one at 80, & visa versa...thats where knowing the land &/or having a rangefinder at hand can be really effective tools...
So go with your 222 mate with 243 as back-up, i rekon you & that rifle are plenty capable of good brain shots on roos, its just a matter of getting a feel for the field conditions & work up to the 200 metre shots as you're comfortable...
The man who knows everything, doesnt really know everything...he's just stopped learning...