You have received a lot of good advice here but I think I have a good, simple cheap solution to your problem. Instead of spending money on another intake/carb, try this first. In the 80s we were all worried about octane and began building low compression engines, (like yours). We made matters worse by adding a cam that increased duration. This combination KILLED cylinder pressure and performance.
Buy a timimg tape, get out your timing light and a vacume gauge. Install the tape and check with your light to see where your INITIAL advance is AFTER unhooking your vacume advance. Hook the vacume gauge to a manifold vacume source and see where the timing is. Also note the vacume reading. With the engine warmed up, begin to increase advance. The vacume gauge should increase rapidly to a point. Check the advance when the gauge slows down its reaction to more advance. Check your timing at that point. I often found that I had to increase initial timing by more than 10 degrees above the factory setting for the gauge to quit climbing. At this point, check your total advance by revving the engine and reading your light/tape. You should be no more than 36 degrees. If it is higher than that, you will need to limit it in the distributor. Before you quit, shut the engine off and make shure that it will start hot with no problems. If it "grunts", back down the timing until it will start normally. Then check total timing again. Reducing the total timing is simple with a Mopar electronic distributor. It uses Mallory parts available at Summit for cheap. It comes with tabs that tell you what mechanical advance they provide. Simply choose one that comes out to 34-36 degrees when you add your new initial timing amount and install it in the dizzy. Reinstall the dizzy and double check your timing. Now, REINSTALL the vacume advance to the dizzy! Part throttle cruise (where you do most of your street driving) requires LOTS of advance! That is why the factory put the vacume cannister on your dizzy. Make shure that it is working with your timing light and tape. You should see a BIG improvement in your gas mileage. I used this technique to take "hot" setups that wouldn't spin a tire on ice and turned them into tire fryers! I was also able to knock down almost 20 mpg with 440 cube engines and low 3 series gears in heavy cars "in the day".
