If you have two fours with progressive linkage the front carb will also end up with stale gas in it. That is why I make sure I open up both carbs as often as possible. (Honest, Officer, that is my story and I am sticking to it ! ) Don
If I understand right Holley was bought out years ago by a Japanese Company. Quality went out the window. Bunch of guys that used to work at the Holley plant in Bowling Green started Quick Fuel. Using old holley specs, but made in America. Edelbrock is American made. You want quality, go with either Edelbrock or Quick Fuel. Edelbrock is my choice. Just my 2 cents.
The new 625 Street Demon is the best out of the box carb we have had on the dyno to date. Atomizes fuel much finer than the other versions of the demon. http://www.demoncarbs.com/1900.asp
I've run both but always liked the performance of the Holley better. Regular 600 vac secondaries manual choke. Has performed reliably for over 10 years without issue