"I understand why the fuel pump cut-off is a safety feature (in case of collision, etc.). But don’t get why continuing current to the choke would be, other than running down the battery (?) Would it possibly ignite gas fumes? If so, that would make it dangerous in normal usage situations, and thus not a common feature."

It is a safety feature.

I posted the wrong schematic (the correct one will not upload for whatever reason).

Study the schematic without the oil pressure cut-out switch and that will isolate the coil circuit away from the IGN circuit.
You don't want to overload either circuit running in an older IGN SW/wiring system and you don't want the choke drawing power from the IGN circuit, especially after having gone to electronic ignition.

____________________________

i assume the cutoff for choke is just a good safety step. remove a hot wire from a supply of fuel. plus a length of wire that could pinch chaffe short etc.
Seth

I asked one owner if there was any visible differences between it and the Factory.s  version. He told me all the ports were the same. Evidently the only difference is its 25-30 pounds lighter.

Hi, I sell these after I rework them, the ports are a little smaller and poorly shaped, I repair the ports that need it and I slot the the carburetor base, some I drill for a small Holley pattern, I would not use these manifolds without some kind of inspection and correction, they all need something.

That's funny, considering that the OEM cast-iron intake manifolds weigh 31 pounds. The aluminum intake, according to John Mummert, weighs 14 pounds.Unless you're into serious 1/4-mile racing, I wouldn't be concerned about the weight difference.   
                       

Cliff have you come across core shift that could be problematic, or is it just more metal inside to remove?
Seth

Yes a little, but nothing that I could not fix, most problems is with the rear ports, they get thin at the bolt hole. These manifolds are cheap, they are not better than stock, I spend about 1 1/2 hours on each one.

I ported my ECZ-B iron intake for testing for the 304CI Y that Ted and I took to EMC.  We tested several intakes and 3 sets of heads before finalizing the engine for EMC.  The ECZ--B made 437 hp and my ported Mummert dual plane made 454 hp.  It took a lot of time, effort to get the ECZ-B to respond to porting but can be made quite good.  As cast it only flows ~189 cfm and the new aluminum intake that I flowed for Ted flows ~184 cfm IIRC.  Here are a couple of pictures of the ECZ-B after port work.  Joe-JDC

JDC

Hi Joe, you always do a better job that anyone else can. what flow bench do you use? mine is a JKM 600 (old)

Joe, how much of an improvement have you seen when the ECZ-B intake carburetor base/plenum has been opened up to two ovals, runners blended into the plenum, and removal of any casting flash/irregularities but no extensive porting? Surely you've tested in stages to determine what modifications return the greatest improvement.         

Just looking at John Muumert's Y-block Porting chart, the stock ECZ-B intake will outflow stock ECZ-G heads. However, once the heads have been worked on, the stock, non-ported ECZ-B intake could be a restriction.