You may pick up some, but that converter is still way tight at 4300. I have seen 440 ironhead combos pick up ET by running converters considered way too loose. My buddy Joe put one in that flashed 6000 at the line, he shifted at 6200, and went quicker by over .05. He didn't like it, tightened it up, and it went slower. Not much, but there was a loss.
My bet is to run a converter that will leave the line at just over 5000, and shift at 6000 if that is what works. I only have about an800 rpm window in my combo.