Sean, you're asking a question that has endless possibilities.
Everyone has their own wants and needs.
So, (in a single reply) no one can possibly tell you all the all the things you can do to a C-10 to improve it.
ie; The list is endless because over the years, "anything" you can possibly imagine has been done to them.
Go here and dig thru the posts. Believe me, you'll be inspired.
After you get a taste of the possibilities, c'mon back and ask any questions you have.
Concours Owners Group Web Forum
Ride safe, Ted