I have a Vibroplex Deluxe Original Left Handed Model that I purchased from Scott at Vibroplex about 8 years back. It was a trade-in with a serial that dated it to 1964, which was also the year I passed my General, so it had some significance to me.
It is all original and the only differences, as I recall, is that the base is obviously reverse design, the horizontal arms on the saddle have two holes on each arm. Normally one side has a single hole for the dit tension spring adjustment, but on the lefty model a second corresponding hole was added on the opposite side, with the original hole being filled with a chrome plated, phillips head screw. Also the shorting switch was reversed resulting in the "bent-tip" tab being on the wrong side so the switch cannot really close properly but can be utilized when needed. I guess they did not manufacture a "reverse" switch bar.
I would be curious if this was the same modification used on your Blue Racer. I have a Vibroplex ad on the shack wall from the early 60's that states "All Vibroplex keys available for left hand operation, $2.50 extra. Of course an Original Deluxe was $26.95!
Regards, David W2JJV