Only to help out, but why would trying another carburator increase fuel pressure? If the carb has a higher demand, it would drop pressure further, wouldn't it?

I don't think fuel pressure is the issue. One time when the jesus clip was hanging up in my quadrajet--listening to all these "experts"--I focused on fuel pressure being too great. I installed a fuel pressure regulator. Reagrdless to the setting, even down at 1 psi, the car had the same performance.

It can be a handfull of things that cause the problem, but I'd concentrate on timing, whether it be initial, advance, or cam. If there wasn't a hot start problem, the first thing I'd do is bump up the initial timing. Next, I'd play with the timing advance.

A while back, I remember reading something about manafacturers retarding the keyways in timing gears as an emission reduction. (You see, people could simply put older--more advanced--timed cam gears in emisson controlled cars and up the hp. I don't know if this still goes on, but if the gear application covers 55-81 Pontiac, something in the timming has to be chopped. Otherwise, these parts would be in volation of federal emission laws, something that manafactures don't want to do.

I have no clue as to how to degree a cam, or check it, so unless you know the cam's timing, it's dealer's choice as to its degree.