Slow, Driving Rustoration 1972 Dart

Do a little more research. I'd stay away from the SP2P and look for a LD4B intake. It's generally regarded to be the best intake period for 318's. They can be a little pricey. Here's one on eBay with a couple of days to go still.

Mopar LD4B intake manifold Edelbrock Dodge Plymouth small block 318 340 360 | eBay

I'd put a used 600 cfm Edelbrock on it with some dual exhaust and see how you like it? If you're trying to increase MPG you're going the wrong way. Once you put a four barrel on there, you won't be able to keep your foot out of it.

Edit: On your cold start video, always pump the gas at least once on a cold engine to set the choke and prime the engine with a shot of gas.