If it revs well in low gears and only dies in high gear it sounds like a fuel related issue. Make sure you have a reasonable fuel system with no restrictions and you'd be happier with a 750 or 950 holley DP.
It is reving well till the top end in top gear. I have had a car in the passed that had insufficiant fuel at high RPM but this feels different it isn't hitting a wall just takes it's time like it is out of oxygen
