Any parts to get my Cuda good gas mileage (other part listed)

If you are gonna make a bunch of trips, this is a great opportunity to experiment with cruise timing.
Many years ago I had a similar opportunity.
So what I did was figure out a way to positively locate my throttle opening so that it would maintain a given setting. Then I made a trip to baseline the mpgs. Then I increased my cruise timing several degrees, and repeated the test. And so on it went until the mpgs peaked, and no additional timing helped. As the timing went up, so did the mpH, so after every trip I readjusted the staged throttle stop I had built, to drop the mpH back to the baseline. When the timing was finalized, I started leaning out the cruise AFR, a little at a time,once per trip;until the engine screamed for mercy, or until she started losing mpHs.
The device I built was nothing more than an adjustable spring-loaded throttle-stop. It was built from an 8 inch length of coathanger wire bent into an S.The S had a very shortleg and a much longer leg; more like a J with a little u stuck on the short leg. The depth of the J was about 1.5 inches and the u was maybe 1/2 inch.
I drilled a hole in a nearby metal-strut (it mightabin the dipstick suppot strut;it was 20 years ago) to act as a guide, and something to stop against.I found in my stuff-drawer an old-style Marrette (wire connector for household wiring). These have a removable brass collar with a set-screw. I found a small one just the right size to slide over the long leg, which I then inserted into the hole.I then draped the J-Loop over the throttle arm;u-end up.I opened the throttle about 1/3, slipped the bottom of the J up to it,locked the setscrew against the metal-strut, and let the throttle close with it's normal closing spring, which I never changed in any way. Then I took a heavier duty spring and hooked one end into the little u. The other end I stretched out back towards the metal-strut, where I drilled a small hole to accept it. Voila, throttle stop!
So now up to 1/3 throttle everything works exactly normal. But then the throttle pin hits the J-hook it stops. If you press a little harder, the throttle continues to open, against the second spring. You control when the stop engages, by resetting the setscrew, and you control the extra pressure required by adjusting the auxiliary spring tension. The whole thing can be removed in a minute, and nothing else has to be changed, and the device does not loose its functionality so long as you do not mess with the stop-collar.
So now to get an initial setting, you just leave the stop-collar slightly loose, and sneak up to your desired cruising speed, stop the car and lock the set-screw. Then prove it took.
To make very fine adjustments, I put a stack (maybe 6)of very thin metal washers on to the long leg, last, and slid them up next to the stop-collar, before finally inserting the coathanger wire into the anchor-hole.If the speed goes up from time to time, I just remove a washer,which engages the stop a tiny bit sooner.
I would have posted a pic but no camera.So sorry.
You can use it for cruise control too! But it does not compensate for hilly terrain :(