Thank you Archie, TerryN and Texstar. This is the kind of information and discussion that I was hoping to see.
Not every package in the repo is designed to build and work with liblua5.1. That is why there is the older 5.0 library.
I was confident there was a reason for using lua5.0 and lua5.1. This explains it. If elinks is the only package left to use 5.0, I can test if it will build with 5.1. But, it is obvious from the list from whatdepends that lua5.1 needs to stay!