Well, eventually I got the whole fuel system rebuilt right down to a newly fabricated 150 gal aluminum tank, and bolted on as many new parts as I could buy. She ran better, but still crappy by my standards so I took the damn thing to a heavy truck mechanic familiar with Fords for a checkup. He ran down a faulty voltage regulator that was part of the problem, but called me a couple of days later saying that he had tried several new jets, but just didnt think there was any way he could get the 570 to work. Its just too small. No matter what he tried, it had a really nasty "whistle" when the throttle first cracked open, and was starving the motor for fuel. He ended up rebuilding the 750 double pumper that was on it before and now she runs like a scalded cat. Its really frustrating that I could not use the new carb, as I bought it on the advice of the Holley factory tech! But, in conclusion... REGARDLESS what Holley may tell you about which is the right carb for a 534SD, my experience has been that a 750 is the SMALLEST you should run. I plan to buy a new 750 double and replace the older one eventually, and I'm on to a guy here that has a performance shop that supposedly can work miracles on old truck heads, so thats my next step to try and squeeze everything I can out of my motor without a radical re-build or replacement.
Regards,
Mike