New bb build fuel economy

I built my 367, for street performance with fuel economy in mind.
But Economy extends to the cost of fuel, so I wanted to try and run 87 gas.
To whit, I thought compression would be the #1 thing. But with iron heads the pressure tops out at around 155 psi. Well I thought about that for a bit. This was in 1998. I had heard that alloy heads could support at least 1 point more compression. I found out later, after more research, why this was said, and also how conservative this was.
So I built my engine for a target of 185psi using alloy heads and a tight Squish, and put the thought of water-injection in the back of my mind, just in case. I put a 292/.509 Mopar cam into it. the pressure was 177psi, close enough.
Well, the beast burned 87E10 right from the get-go, with full-timing no less!
I didn't like that cam, pulled it out, and swapped in a cam three sizes smaller with no other changes.
The pressure jumped to about 195.
This combo made tons of torque, good power, and great fuel-mileage. In fact so good that nobody believes it when I speak the number, so I rarely do. Yes it still runs full-timing on 87E10. It now has over 100,000 miles on it.
The point of this story is that the entire purchase-price of the closed-chamber alloy-heads was recouped in fuel savings within three years as a DD. Since then it has been saving me gas money every time I start it up.
Lest you think that 195psi is a fabrication, I did a survey here on FABO several years ago, and found out that a few members here are running the same and more, to even a tic over 200psi.
There is IMO, NO DOWNSIDE to running these high pressures, for several reasons;
1) your engine is rarely at WOT, so rarely creating these high pressures
2) Your engine is only capable of inhaling a full load of air , for a very narrow rpm window. and only if you cammed it up to do that, and matched all the components to that cam.
3) When cruising in a steady state, your throttle is only open as far as it needs to be to create the motive power for that circumstance..... so the EFFECTIVE compression ratio is NOT nearly what the math says it should be. My Scr to achieve that 190+psi was 11.3. But if my car only requires 35/40 hp to cruise 65mph, maybe the Effective Compression ratio, might be 5/1; IDK just guessing.
If I gear that beast to go 65mph @1600rpm, the throttle will have to be quite far open to get the required air. If I install a small-primary carb, it may get up on the mainjets, where I can control the actual fuel going into the engine, very accurately. That thinking is what got me the very high fuel-economy.
And it can do the same for you. Camming it for that very high pressure is the key.
But if you want to run big-number rear gears, well then this is not gonna work for you. Unless you have an overdrive.