No, I think there's just honestly no way to guarantee a score like that. There's tons of people with NBMEs averaging in the 230s or upper 220s who who scored 250+, and then people the other way who had a couple in the 240s and then scored in the 220s. Predictability seems like it's becoming harder this year, I guess we'll see when the new score predictor data comes out (although we probably won't care by then lol). For the vast majority, it seems like UWSA2 is holding up fairly well, being a slight over-predictor in most cases. 18 is an interesting one, because it seems to be obviously not predictive if you take it way in advance, but more predictive in the 240-250 range taken within a week or 2 of the real thing.
The best way to guarantee a good outcome is to study your ass off and stop trying to interpret the scores tbh. It is apparent, both from people on this thread, reddit, and irl according to your friend, that the numbers are all over the place in terms of predictability. The forms are just so variable. You have people majorly underperforming, and then you have people majorly overperforming (like 10-15 points above every prediction). Focus on giving it your all and then at least you can say you busted your butt for whatever score you get, and there's nothing else you could have done. Regret would be the worst outcome for me, and I worked hard to make sure I have no regrets. Whatever score that yields me....it's what it is.