Trick Flow 440 heads, The Real Deal?
I would disagree that that is the plate for an RB. I have one on mine with the 270's and it fits almost flush to the heads. If you want to measure yours corner to corner and let me know what it is I can check that against mine and see. With that big of a gap I would be worried about the RTV blowing out with any kind of pressure in the crankcase.