Probably not. Unless the previous intake and carb were not functioning properly.
Edelbrock makes a manifold for the 4.3. I'm running a 500cfm performer carburetor on my '31 Ford Pickup with 4.3.
The Edelbrock carbs work very well right out of the box, so if you have the correct intake manifold it should bolt right on with no problems. The Edelbrock website has all the info you need for tuning and connectivity.
It depends, if you get the exact same carburetor, then no, but if say you upgrade from a single barrel carter to a 4 barrel edelbrock then yes, but if you already have a 4-barrel carb and manifold then you may need a adapter which is inexpensive, but you could also get lucky and it may bolt right up.
the edelbrock website should have that info.
The firing order is the same.
With the intake and carb you are running you are fine on flow. It's all in your carb adjustment. You may have the idle set too low, the floats too high and it's flooding out, could be the wrong size primary jet size. A lot of guys swear by them, but I never had much luck tuning an Edelbrock carb.
I have never seen a cast iron edelbrock intake so I would think not.
sure you can, you just need to get a 4 bbl. intake manifold for the 318-340 engine, edelbrock makes them and summit racing or jegs sells them.
To the intake manifold.
Chevy 265, 1955 -56. Want to sell it?
25 ft./lbs.
from the intake manifold.