scale certain verteces to desired dimension

In Object Mode, it is possible to give an object dimensions.
Is it somehow possible to scale selected vertices to desired size? Dimensions panel is gone in Edit Mode.

I am making 3D printed nose cones for hobby rockets.
Here is an example:
http://kodu.ut.ee/~nils/source/sugar_rocketry/3d_printing/32_mm_nosecone/32mm_rocket_nosecone.blend
I would like to scale bottom(cylinder) and top part separately to desired size.


Top viewport: the selected vertices/edge in the file. Enabling edge length display in 3d view properties shows the length
Bottom viewport: the faces those are connected to are severely non-planar n-gons because the outline vertices are lower than the tubes

One way to size a cylinder/pipe is to select the faces in face selection mode, alt+S to shrink/fatten with even option on, and at the same time look at the length of the reference edge you have or created.

Another is to construct the thing from separate objects and combine them using boolean operations, Bool Tool addon helps with that. Once sized correctly, the booleans could be applied and the mesh would require minor clean-up, because it’s a 3D print.