Hi artie60
Welcome to the site, UDP ports are just like the TCP also, in theory any number can be used for either setting. The important things to remember about them are to not use a number that is use by another program, choose a number between 1 - 65535, and to make sure it matches any numbers you have in firewalls, routers, or dsl modems with Nat ability.
Hope this helps you.. there are no numbers that are best really.. its actually best the bigger variety we use...