It is somewhat like asking,... if Anderson fought Weidman a couple of years before would Weidman still win?
Seriously though, Wanderlei was the top dog in Pride. Before Pride fighters came to the UFC and got washed up and lost, UFC fighters went to Pride and got beat, and then beat. Chuck Liddell one of the UFC's most dominant champions ever was KOed by Rampage. At this time Rampage was a total beast, he physically overwhelmed the majority of his opponents, and had a strong mix of striking with wrestling.
Wanderlei wrecked him twice at this time. Sakuraba who was known for handling bigger and stronger opponents so well, Wanderlei wrecked him three times. This was at a time Vitor fought in Pride, along with elite grapplers, and strikers like Igor.
None of em wanted Wanderlei at this point. He was pure Fury,
Don't get me wrong I think Weidman may still beat him, but people who didn't follow Pride have no idea how SAVAGE Wanderlei was. At the beginning of Mirko's career Wanderlei fought him to a draw. He remained confident he could fight with anyone after Mirko then went on to destroy everything he saw with high kicks.
If the fight was in Pride I would take Wanderlei, I might even think he could fight with Anderson Silva and win in Pride, just considering how he owned the Pride ring for a time.
Weidman may beat any version of him sure,
but seriously Weidman has never in his career thus far seen the Fury of the Axe Murderer that was.
Perhaps he was on steroids then big time, (but also note myself included many Anderson admirers like to think he only used roids late, but then some of them don't like Wanderlei so they assume he was always pumped with roids) but that Wanderlei perhaps along with Fedor terrified everyone in mma.