"so what's a good size in terms of width and rise? "

Dude, just call your local bike shop and see if they've got a used set of mountainbike risers or flat bars that somebody left when they upgraded their bike for $5 or so.

Then, mount that on your bike, and ride it around for a while and chop it down to the size you want with a hacksaw.

That way, you're not screwing up something nice if you cut it too short, and you can mess around and figure out your fit, and then order something nice once you know what you need.

Failing that, just buy a set of generic Dimension / Origin8 1" riser bars for $20 or so and call it a day. (You'll need a hacksaw and preferably a saw guide to shorten things properly.)