Dr AL
Home Depot sells Insulated heat shrink butt connectors in different sizes. Here is an example, http://www.wiringproducts.com/contents/en-us/p631.html
Since those wires don’t carry a load you could strip them back solider them and add a few short lengths of shrink tube, less work, faster and cheaper (which makes the boss happy).
Sfrankland, How fast must one be going to get the reverse rev limiter to kick in?