Sorry – I misunderstood the Vee-shape in my earlier post, to mean in the finger-clamp itself.
Though not universal, many Vee-blocks are made with a small rectangular groove along the base of the Vee.
I think this is more common on blocks made on a shaper (indicated by the tooling marks), but will provide some clearance for the tip of an end-mill used for the sloping sides.
It can be cut with a slitting saw or if shallow enough, a slot-drill, as a first operation.
A tilting vice is advantageous for this sort of work, but turn the block round for the finishing cuts to make the Vee-groove symmetrical by balancing any slight tilt-angle error.
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One little detail addition to a finger-plate as shown by Jack Hobson, is a small tapped hole in the broader vertical face, to take a simple end-stop for repeated work. This is also applicable to larger Vee-blocks and machine vices.