Consider the image below, where the selected vertices form an incomplete circle (that was derived from a circle), which measures 12.5mm. I would like to change the radius of the circle formed by the vertices to instead measure 12.8mm.
With the vertices selected, and with 3D cursor set as the transform pivot point, I can press S (scale) then Shift+Z to scale the circle, and it scales as I want it to, but it will only scale based on a percentage, rather than an absolute measurement.
I would like to type .3 to have the radius grow by .3mm.
I know how to do it the long and tedious way by adding a new circle the size I want, then reworking all of the geometry, but I really want a fast and simple way to scale up a circle-like shape's diameter by absolute dimensions.
EDIT: It's possible to use a percentage difference calculation, which in this case is a difference of 2.4%, which would be a scale operation with a value of 1.024. But it would be nice to use dimensions instead of reverse-engineering a percentage.

