Ok...not a hand loader but if I want to lengthen the .500 Smith chamber to accept 50/110 brass with a .500 bore and shoot .500 bullets..What is the process and die needed to make this work? Thanks!

Easy; you will need a 50-110 sizing die, but one that will make the brass to fit your new chamber, which will be about .010 smaller. You might be surprised to learn that a standard 50-110 die might work as is. And custom sizing dies will cost a fortune, as they have to make a reamer for it, which they will never use again. So plan on spending $300 for a die. And your expander will need to be .010 smaller too, but those are easy to make or alter.
For this animal, you will certainly need to be a hand loader as you are creating a wildcat.