I am still tooling up my blacksmithing side of the shop, so today I tried to make a simple swage block. I have a 12 ton press with only 3/4" travel, but I was able to get 3 different radii on one side and a dishing die on the other. 

Good job.  You'll find that little block infinitely more handy than a big lump of iron that's nearly impossible to move.

I use one similar to yours and love it.  Don't think you have to get all manner of shapes into one block, either.  You can make up a dozen blocks, however you like, and swap them out as needed.

You can weld a couple of pieces of flat bar on the sides so it will rest on the jaws of a post vise, or put a shank on it for the anvil.