[joeveto]

Do yourself a favor, and play with the timing. Give it the most advance it can take, without pinging.

Pick up a set of performance advance springs, and recurve your distributor. Pull the vacuum, throw in 10-12 degrees base. Then, with the vacuum still unplugged, check your timing at 2500 RPM. You should have your advance, "all in" by then. The maximum amount will be determined by your advance springs. Play with the springs until you find the sweet spot. I'm not sure what it is for a 307. But for a 350, you want 34-36 degrees. Of course this can be affected by vehicle weight, gearing, etc. I'd say for the 307, you'd want to run a little less.

Once you have the above figured out, you'll need to adjust your vacuum advance. You'll also want to decide if you want to run it off the timed port or the full manifold vacuum port. Which is another subject, altogether. I usually go with full manifold.

Once your vacuum is connected, you should not feel any shuddering at freeway speeds, low throttle. If you do, your ignition is too far advanced. Just take an hour or two, and play with it. You'll learn a lot. And buy yourself an advance timing light. It makes life easier. Or degree your balancer.

I too, am here in Ohio. So I know what you mean about the weather. I'm waiting for the weather to break, later in the week, to finish my cam swap.