No... Generally, folks tack weld hunks of angle iron on both sides of the CC.... The lip,of the angle iron, is at the height of the top of the FB/CC opening... Make the lip wide enough, your perforated plate can be set on the lip, providing a "dissipation" of heat and smoke in an even pattern in the CC... 2X2 angle will do even if you have to tack weld a couple of strips to narrow it enough for your perforated plate.. or tuning plates to rest on...
Doing those changes allows for free flow of heat and smoke through to the CC... AND your FB will run a lot cooler and reduce fuel consumption... or so it says in fine print somewhere...
That angled deflector plate was installed to keep the heat from the first part of the cooking grate... That would have been a good idea if the smoker was operating as a "forced air" cooker... unfortunately, in a natural draft situation, it seems it's best attribute is choking off air flow..
With the FB/CC opening free to allow air flow, the upper and lower air inlets can be adjusted for a smallish controlled fire and the upper inlet moves heat in the FB through to the CC without adding oxygen to the fire... not unlike the fan on a forced air furnace theory...
A tightly sealed smoker is pretty much a necessity for all this to take place... any air leaks disrupt the natural draft...