Small block intake

Another option; keep the 2 bbl. It's good for up to ~3,000 rpm. At 70 mph you're only revving at about 2,300 rpm. The first thing to do is to replace the timing gears. The nylon gear your car came with usually lasts about 100,000 miles or a little more. If the teeth chip off it will skip a tooth or two and bend push rods and valves. How do I know this? Yep. Someone mentioned retarding the cam timing. Never tried it but it should work. More power. [Those were bad years for emissions = detuning engine power].

Next thing to check is the heat riser valve on the pass. side exhaust manifold. It must move freely.

If you have an EGR valve, you can try it with it or without it by disconnecting and plugging a hose.

Distributor modifications can be made.

Your car weighs over 5,000 lbs. with 3 passengers. It's a lead sled, and the 360's working hard. Someone mentioned 3.23 rear gears. A good choice for that car. And probably wouldn't change the mileage much.

Happy Motoring