Just mix 3:1 washed sharp sand and cement...
barely wet, but well mixed. (Use a consistent measure to retain the colour throughout the work. Dependent of the stones etc a bit of black pigment takes the 'green' edge off usual mortar) Hoist a lump onto a trowel, hold it in your hand and use a pointing trowel in your 'best' hand to guide the mix into the voids.(Being barely wet, you will not stain the stone edges etc) Use the edge of the pointing trowel to 'pack' the joint (and avoid future deterioration). Use the bottom of the trowel to 'flaunch' the joint and 'polish' the mortar mix to a smooth finish - using the metal trowel will bring just enough moisture to the surface of the joint to make this easy (ish).
Use silver sand if you want a tough old joint.
I look forward to seeing your builder's accoutrements in the 'For Sale' section sometime soon. A Rolhoff wheelbarrow? Wow!

(And several unused bags of whatever you mention.)