Aerodynamic upgrades?

With computerized timing controls, and EFI, yeah you might be able to cruize efficiently at 65=1600, but I would think such an endeavor would take a special cam.
But getting my 367 to burn efficient at that low an rpm was not easy.
I installed a dash-mounted, dial-back, timing module with a range of up to 15 degrees.
I only ran that 65=1600 for one summer, until that cam lost lobes. With the smaller cam (223/230/110), as to mpgs, I found that running at 1600 in 2ndOD versus 2050 in firstOD@2050 was just not that much better.
My new cam, 230/237/110 does not get mileage anywhere near the former, and so I ditched the A833od in favor of the commando box, (still with the .78GV behind it) and economy at 65=2240 is what it is .The New cam combo runs at 65=2240.
My current timing set-up, runs ~14initial+10Mechanical@2240+22VA=48 plus whatever I dial in. I run a minimum of 54*@2240, and sometimes up to 60, and one time at 63*. You cannot run that with just a distributor, unless you manually crank it over, and promise not to floor it.
As to aero/drag , I think my stock-body Barracuda must be pretty good. When I stuff it into neutral at 65mph, it takes forever to coast to a stop, even with the low tire pressures that I run.