My database only houses non drafted prospects from the last few years (in addition to drafted), as I really generally just care about the characteristics of players who end up succeeding in the NBA.......so it does lack a lot of the more fringe guys (like the Knights of the world), to make a good comparison.
With that said, 40/20......no one in the possession era has done that, that has been drafted. The closest player was Mike Muscala, who was 37.7/22.4. In this draft, two guys are in the ballpark.......Vernon Carey Jr. 39.2/19.3 and Luka Garza 42.3/17.4.
The hardest part is the scoring metric, as only 10 drafted players in the possession era have scored 40 or more points per 100 possessions.....and 7 of the 10 were guards or wings, so the rebounding isn't really realistic in that regard.