The 351w does not have a valley pan gasket, just the 351C/M and the 400 and 460. You got the correct gaskets. As for those holes, I have no clue ether.
Do your self a favor, put a dab or small bead of silicone in the corners where the rubber gaskets accrost the top of the block meet the gaskets on the head.
Steve
86 Bronco, XLT, 5.0 EFI, EEC IV, AOD, IFS, limited slip front and rear, 3.08 gears, Tilt steering, factory AC