I wasn't dancing around the subject. The point was not the build, but maximizing efficiency for all purposes, no matter what the build. If we instead look at the build design to first set options for reaching the design goals, then we talk about how we would design the build and why. But, we do not have any parameters yet. To suggest a build that does not address specific goals would mislead some into just taking that build for themselves, and getting bad results because the build was not to their goals, in their car, with their budget, or their skills, with their requirements in-mind. See what I mean?
Obviously a build design for a 2600-pound 5-second BBF would be different than one for a 4400-pound 8-second car, even though they both need similar power numbers. Now, let's complicate that by adding mileage requirements, unknown weight, gearing, tires, driving style, parasitic losses, and no performance requirements, etc. 350hp and 25 mpg or 600 hp and 18 mpg? Or maybe it's a max effort, and we want 800 hp and 25 mpg in our unknown car to reach unknown performance goals. So, we don't know if all he needs is a rebuild with carefully selected parts and mods to the pistons, heads, cam, intake, exhaust, ignition, fueling, tires, body, etc. Or, maybe it's major changes to everything and state-of-the-art multi-fuel injection with eight crank-triggered multi-spark coils, water injection, 6 or 8-speeds, carbon fiber body panels, or whatever.
I hope you don't think I'm avoiding the issue, but in reality I am avoiding a lot of work of making an imaginary example package that meets nobody's goals. If we are to take the time and effort to really plan a realistic package, I'd like to do the work for something that will actually be done, and has a reasonable chance for success. Call me selfish if you like, but making that kind of effort just for kicks is not in my cards today.
Examples? 1970 Fairlane 429, WR toploader, 3.70 gears, 28" tires, 3450#, head and intake work, mild performance cam, custom ignition curving and carb tweaking, no dyno, no track, 21.6 average highway mpg. City mileage unknown because he's heavy-footed. 1973 Mustang 460, C6, GVOD, 3.50 gears, 27" tires, extensive mods from low-tension rings to filled and worked heads, custom tuned exhaust, etc. Full electronic ignition and closed-loop fuel injection, dual AFR, EGTs, etc. 4250 pounds, dyno and street tuned, 487hp/543tq, (corrected) and instant ECM data feedback of 26.3 mpg at 65mph sustained and level cruise. I've already given other examples, including generic ones like my stock 3/4 ton truck that now saves $900 a year in fuel with slightly increased power.
If I were to design a generic build trying to balance cost with performances, it would have changes all over the car, and the engine start with a D9TE-BB block, D4U 429 crank, extensive blueprinting, precision specified machine work, a month flowing runners, HE pistons for highest efficiency and best hot strength, to handle boost to provide 650-800hp and 25+ mpg (depending on the chassis to start with). A big part of it would be staged injection, dual-fuel EFI with fully programmed distributorless ignition with features such as fuel-cutoff on decel, electronic wastegate control, full trans and lockup control, peak cylinder pressure crank angle detection, etc.
Possibly less expensive (though far more intensive) than your serious stroker build, offering equivalent average power, and much higher mpg to boot. However, this then begs the question of why? Is this the best route to meet the goals? Possibly and probably not, and there are many other options available, many less expensive or more efficient or both. Again, we need goals.
Hey - if you have cake, eat all you can get. Does that answer your question(s)?
Below is a simple dual-fuel injection plate I made from a carb spacer. This one has four injectors to feed over 300hp of additional methanol during high power and/or boost. The engine runs on 87 octane granny gas the rest of the time. The staged fuel addition is progressive, seamless, and automatic: