i think the closest sure lock/crux combo is gonna be the overseas crux formula but as for the sure lock being similar you would have to mess around with surface since you already have it drilled. GI 17 seems to have its own reaction shape. i threw the sure lock and the alpha crux and the crux formula which i thought would be a stronger crux. it was more of a weaker sure lock, it had the sure lock motion but tamed down (still a really strong ball). i had put the same layout on the crux formula as the alpha crux. the sure lock will probably roll earlier than the crux prime because the core is slightly stronger but i am not sure since i haven't thrown one. so if i wanted to get a sure lock closer to a crux prime i would try maybe 3000 or 4000 sanded.
sorry for a long answer, the crux series is one i have always liked