If I had to pick six guys in their prime to play one professional 48 minute game They would be Wilt, Timmy, Bird, MJ, West and LeBron.
LeBron because he makes substitution possible at every position. In his prime he was able to defend five positions as well as play offense at all five.
This is a different question than "who was the greatest", really. For me that was either MJ or Wilt, take your pick. But the six I named would out rebound, out defend, and out score any other six you could put on the court, more times than not, even if your next six were also all time greats.