ELOC time.
According to HSDS, Kongdong Sect grandmaster Mulinzi was a master of the Seven Maim Fist:
宗维侠强道:“七伤拳是我崆峒绝技,怎能说有害无益?当年我掌门师祖木灵子以七伤拳威震天下,名扬四海,寿 至九十一岁,怎么说会伤害自身?你这不是胡说八道么?”张无忌道:“木灵子前辈想必内功深湛,自然能练,不 但无害,反而强壮脏腑。依晚辈之见,宗前辈的内功如不到那个境界,若要强练,只怕终归无用。”
Furthermore, according to Xie Xun, he used Reverend Kongjian and Zhang Sanfeng as examples of people who could possibly master Seven Maim Fist:
谢逊又道:“倘若我内力真的浑厚坚实,到了空见大师、或是武当张真人的地步,再来练这七伤拳,想来自己也可 不受损伤,便有小损,亦无大碍。
Certainly, Xie Xun himself did not have sufficient internal energy to start practicing Seven Maim Fist, and that is why he got damaged internally by it.
I'm sure Mulinzi learned Seven Maim Fist before his death age of 91. Judging by the description of his accomplishments, it seems to me that Mulinzi should be on par with Reverend Kongjian, if not better.