I think DM-7.1 or DM-7.2 has correlation for coarse-grained soils and friction angle. Your term "drained shear strength" is somewhat vague as we typically consider drained properties to negate the buildup of excess pore pressures, which to me is the frictional behavoir described by the Mohr-Coulomb friction angle. I think you can use N-values to get at the draineed friction angle and then use the friction angle and your confining stress to arrive at the shear strength, which would be a value for drained conditions.