Is it worth the time and trouble to reface an old anvil?
Refacing an anvil is not an easy job. My short answer is to just use it as it is until you find a better one.
If you use welding rod to build up the face you will have a lot of grinding to smooth things out and you will probably take the temper out of the surrounding steel meaning that you will have to heat treat the whole anvil.
Your other option is to have the surface milled to take down the high spots. This means you will have less surface thickness over all to work with, although it will be flat. With this you shouldn't have to heat treat it.
All in all considering time and money many people just find it cheaper to buy a new anvil. Try www.blacksmithsdepot.com www.piehtoolco.com or www.centaurforge.com or www.oldworldanvils.com for price comparisons on new anvils.
It is tough doing some of this work alone I would check www.abana.org for any associations in your area. It is great if you can talk to actual people and see demos close up.