Intake Manifolds

It looks like your trying to get blood out of a stone, I'm all for 2.2l,/6,273,318 etc.. Builds and there are minor gains to be had down low 2000-3000 rpms with basic hot rodding, but it's basically gonna be what it is with what's available to us. There's no magic combination to get 360 cid + low end torque from a 318, if you really want strong down low torque build a bigger engine and or some kind of power adder. If a decent put together 318 makes enough low torque to satisfy you then fine, but you can try to over design/fret about the build ain't gonna do much more then the basic hot rodding set up that's been laid out over and over again.

A 5.2l magnum with a minor cr bump and headers and the right cam, beer barrel intake is probably max daily driver type performance out of a 318 especially with OD and gears.