Never had Webers on any V8's but I've been running the 44 IDF's on my VW for 10+ years. When the idle jets aren't plugged they run great! But being the jets are so small it seems they're plugged up all the time. I've tried all kinds of filters to keep them clean with out much luck. Also they are pretty expensive to tune. You have main jets, idle jets, emulsion tubes, air bleeds, accelerator pump jets and venturies that can all be changed and your looking at $5 each at a minimum for these parts and each carb has 2 of each, times that by 4 for a V8 and your looking at 40 bucks just for a main jet change.
That being said they do look awesome and will give you the most average power of a carb system.
JMO,
Rex