Can this softbox fit into the AlienBee 800?

I am considering buying the AB800 light and have this 3x4 softbox: http://www.fjwestcott.​com …8-softbox-silver-interior

1) is it too big for the AB800 to support and power evenly from corner to corner?
2) this softbox has 4 basic rods, where do I get a speedring to make it compatible with the AB800?

http://www.paulcbuff.c​om/speedrings.php - is it the first one?

thanks!

Why not order the Westcott "item 3500 - speeding for all Alien Bees lights"? It's listed in the instruction manual for the Westcott softbox you linked to. See the download instructional manual link on that page. I'm just trying to simplify things for you by suggesting you get the softbox manufacturer's speeding.......

Best regards.

Perfect answer thanks! Would you have any idea how I can counterbalance the frontal weight if I put a giant softbox on the tiny alienbee?

I have a 4-foot octobox that I use with both my Elinchroms and my Einstein, which has the same mount as your AB800. It'll be fine. Personally I wouldn't keep the softbox stored mounted on the light long term, as the Buff light mount clamps are kind of janky IMO, but that's a separate issue.

Get the correct speedring and you're good to go.