I'm surprised that Porterbuilt didn't offer a sway bar as an add-on sale when you bought their kit. Seems like they would have offered the info that a standard C10 sized sway bar does not work with the setup they sold you.
Check out Speedway Engineering, they have virtually endless combinations of setups as you can buy the individual components to suite your needs. I'm sure if you calculated all of your dimensions and give them a rough estimate on vehicle weight, motion ratio of your front suspension and current spring rate, they could match up a bar rate for your intended application.
http://1speedway.com/index.php?route...tegory&path=76