Good luck with the install. I'm finally done with both floor/braces and trunk. Trunk took for ever, all butt welded in. Tons of welding/grinding/more welding/more grinding.
Take a look at the hockey stick braces. Mine had an extra rib bump where my original floor tapered to flat (before it had to clear the brace like the other ribs). Maybe the 68's are different, or the coupe has a rib continuation? I had to cut the rib in the hockey brace, dolly it flat, then reweld/grind. Viola, gone.