Emgo bar end mirrors installed. Figured it out.
1. Removed and discarded the internal expanders and ugly bolts which are metric. Replaced with 5/16" dia. button head 1.5" long that fit well.
2. Made a drill guide: Cut two 1" pieces of PVC pipe, 3/4 & 1/2 dia. and slid them into each other. Filed a shallow groove along the outside side of this 'collar' to fit over the seam inside the handlebar tube. Found a 1/4" ID metal tube 1.5"+/- long and shimmed to slide fit inside the PVC pipe collar. [a piece of old sawed-off airgun barrel shimmed with
masking tape wrap].
3. Found a 7mm drill bit in my tool box, apx size for the 5/16 x 18 tap I had [17/64" also works].
4. Vised and drilled out the 1/4" ID tube to 7mm.
5. Slid the shimmed metal tube into the PVC pipe collar I pushed into the handlebar ends and using it as a guide, drilled into the plugs welded inside, apx 5/8" for the std plug tap. Threaded holes to depth.
6. Filed shorter the mirror base expander bosses to the depth available inside the bars. Inserted the 5/16" bolts and tightened.
7. The mirrors are installed.
8. Still need:
A. two fender washers to go between the mirror and end of bars to cover the gaps and maybe thin rubber shock washers to make twisting adjustment easier.
B. something to fill in the gap between the end of the grips and the end of the bars where the factory plastic caps were.
c. two decorative bolts to fill the old mirror rod holes.
One hopes you know how to use a file, saw straight, drill carefully, and use a tap properly if you attempt this. I wore ear plugs and safety glasses. Maybe 1.5 hrs on this cloudy evening.
Camera's dead. Pics when I post of the whole bike... coming soon.!
I feel less blind already.

. RAH.!!!