1. You can't use one single 4 foot piece with a single slant. Will not work.
You can have 2 gangs side by side, or you can have one gang behind the other, but you always need 2 gangs opposing each other or the disk will just roll off to one side and not do much.
2. Welding a perminent angle in a disk is not the best idea, sometimes need shallow or full cut. instead drill 4 holes and make adjustable with a bolt.