[storm9c1]

I agree. A canister won't add vacuum. But it will store vacuum and keep it more stable if it bounces around due to the cam.

I think the next step is to maximize your vacuum. Warm up the truck then hook up a vacuum gauge and tune the mixture screws to get max readings at idle. Do the same with base timing. You may need lots of timing. Possibly 16 degrees or more. As RPMs increase, use the idle stop screw to bring it back down, but with that cam, you may need to idle at 1000RPM regardless. Another possibility (and a bit of a hack) is to use the vacuum advance to boost your timing at idle which might boost your vacuum signal a little more. Either way, if you have to run a ton of initial timing, this also means that you need a distributor with a shallow mechanical advance curve to get you to the all-in timing of 34 degrees (+/- a few degrees) with that much initial timing.

Either way, the carb will need some parts changed (as mentioned earlier) for this as well. An Eddy carb would need metering rod and spring changes for sure, so just swapping the carb isn't going to solve it. A mechanical secondary carb may also help slightly. But may present other problems.

A cam like that takes lots of patience with tuning. Might sound good -- but such a low vacuum signal makes for lots of tuning issues.