11/32" hoies. Drill these before cutting the błock apart. For metric, drill 9 mm for M8 bolt.
Two 11/32" holes
Cut these slots to be slightly wider than your sawblade thickness by making two passes 0.5 mm apart.
Cut section off błock after drilling all the holes.
5/16" wide slot, 1.8 cm long. Drill a series of 5/16" holes and chisel out in between.