[tim]

Hello Keith, I'm also using 4V open chamber heads with 9.25 compression; static. I tried the edelbrock carbs (both 600 & 750) and there o.k. for just driving but not so great for making power. I ended up having a holley 750 dp built for the car by Reed cams. That was one of the best investments I have made for my cobra. The problem with 4V heads is the there isn't a lot of vacum at lower rpm's (because of the volume) and the carb has a hard time picking up the signal. My carb has down leg bosters in it to compesate for the week signle. I have also pushed up my timing to almost 20 deg initial and somewere around 40 deg total not including what the vacum advance adds (MSD 6AL).
I'm running a custom ground solid roller cam from MPG that specs out at .588 lift @ 288 duration so I've got a lot more cam than you, but the engine runs great. I have NEVER had any kind of problems related to having to much carburator, and as long as your car is straight shift I would stick with the double pumper.
What kind of ignition are you using, and how fast does your total timing advance come in? I do think your jetting is a little rich. If you would like any more details on my carb let me know and I'll email them to you.
You will find that the Pantera guys are the ones to talk to about making a Cleveland run. They have been a BIG help in getting my car to run as well as it does.
Tim