any history records ..? not those of SGYY though
ZZTJ and the relevant SGZ's (Liang's and Liu Bei's is on kongming.net I believe) though it isn't a question with a 100% answer.
I think the reason Liu Bei went from wandering mercenary general to Emperor is simple: Chi Bi gave him breathing room and a base. Apart from Xu, which he inherited in less then ideal circumstances and lost through a coup, Liu Bei had not had a secure base or time. He was either in somebody's employ or in a insecure position that was quickly attacked, both of which summed up his position just before Chang Ban. Chi Bi pushed Cao Cao back, provided an alliance that acted short-term as some protection and thus time. Also with Zhou Yu taking awhile to beat Cao Ren, Liu Bei was able to nick in and create a temporary base for himself in Jing. Then Liu Zhang opened up a window of opportunity for Liu Bei to get a secure base.
So really, the opportunity for a man of Liu Bei's immense ambition/drive and abilities only really came after Liang joined but not due to Liang himself. It was Liu Bei that seized it, with his political wiles and drive to exploit the chance+miliatry ability that was needed. Liang was helpful but until Yi fell, when Liu Bei needed an administrator he could trust, he wasn't really vital. His advice at the time was erratic and the roles he took, like diplomat and reinforcing commander, could probably have been done by others.
Or what Elitemsh said.
“You, are a rebellious son who abandoned his father. You are a cruel brigand who murdered his lord. How can Heaven and Earth put up with you for long? And unless you die soon, how can you face the sight of men?”