I'm with Seafire, although I'd go the 20 TACTICAL for the longer neck and extra wildcattiness.
I have worked up a couple of 204s, one was a troublemaker and the other considerably more willing. Both are rather sensitive to case concentricity, your brass HAS to be good, or ultra-prepped, or you'll MISS.
What I love is watching the shock wave, the recoil is really next to nothing. On meat, never had an issue, but was using Blitz King 39s in all situations. Overall, however, I think the 204 is throated too long from the factory, at least it has been in my experience, and it also runs pretty darn warm, heats up quick in the dog fields.
So, when I build my 20, it's gonna be a short throated TACTICAL where I have to prep all the brass beforehand. Looking forward to it, actually.
