Horsepower with mileage options

I have a David Vizard book, called Performance with Economy.
In that book is a nice little chart comparing compression increases to power increases and to economy increases.
That chart shows that a compression increase from 8.0 to 11.0 is worth 5.2% power increase, and "the mileage gains (percentage) will be about double"
Now the last time I quoted that here on FABO, I was told that the power increase would be waaay more than just 5.2%; probably 100% more! or 10.4%. I can't argue that point, cuz I have no data of my own. But I have to wonder; if Mr.Vizard was off by such a huge factor in compression, was he also that far off in the economy prediction?
_______________________________________________________
In any case; to put a 318 into the performance arena,with bolt-ons, is gonna throw economy right out the window. You're looking at gears,a TC, and a 4bbl set-up, at the minimum, plus maybe a lil cam. What's that come to in Dollars? I'll guess $2500
Now, what would it cost to find an LA 360 core and pump the compression up, and a quickie valve job? And now, you can keep the gears and TC you now have, and stick your 318 cam into the 360, and keep it as a 2bbl. I'm guessing a lot less than $2500.
More torque, More power, and probably less fuel consumption.
Or you can leave that Lo-Po 252 cam in there for a ton-O-fun,and not including all the horsing around you're gonna be doing, I bet it still makes better mpgs on the hiway.
I tell ya, I wouldn't spend a nickle on a stock long-block-318-automatic, beyond what I had to to keep it running .