Well I assume he came to the forums to gain some insight into how much to trust his low scouting.
Here's an opinion: Don't trust your 6 HS Scouting at all, instead focus more on the Current ratings for HS players and put them below any usable major league players you have on your list.
The biggest key to your original question is the fact that quite a few players will require being drafted in the first round and aren't worth drafting.
If the guy you're considering at #5 has at least a vR of 50+ currently, then he's at least decent. But just consider the tradeoffs of not knowing vs knowing better what a player will do.