milling heads for comp ratio increase

Yes I know exactly what you are saying and it all makes great sense. However not only do most of us here not have those great opportunities (as I said, 360s are very sought after here, and getting very rare too, we only got that engine for a few years in a few models. We just don't have the numbers that you do) but especially in my city, which is very limited compared to Sydney Melbourne Brisbane (all East coast). Also, I don't WANT a 360 or 318. I had both of those, as I said, I sold the 360 because it was too big for what I wanted and I got all my money back so basically got the car for free minus the engine. The 318 I had went into another vehicle. The 340s are both earmarked for my E bodies. I had the 273 lying around and want to use THAT one as an economical daily driver. And in any case, it hasn't cost me a heap, and i had some parts lying around that suited that engine well. Also I have never had a 273 and now I will have one. It's not the ultimate power I want or need (have more Mopars for that). I just want a nicely improved economical 273 for my ute. Hope you understand.

As an example of the differences in prices, about 11 years ago I bought a complete and running (but unknown condition) 360. Came out of some imported US car. Had all the fruit: ignition, alternator and Holley carb. I paid $2000 which was a very good price at the time! And this was 11 years ago. I was lucky, all except one bore had very good compression, that turned out to be a burnt valve which I replaced. New head gasket, Sig Erson 290 Cam and better springs, new DRTC, single plane Weiand and a TQ plus headers and twin system and that engine in my Challenger was a great engine - I took it up to 130mph and it was still accelerating (the 2.6 diff helped there).
Yes I understand liking a nicely tuned economical daily driver. Again like my wife 66 Barracuda. the previous owner had put dual exhaust on it and I put the four barrel and a LB4D. It wasn't economical by today's standards and it was a fun little Cruiser I guess. Here's my full $0.02 on these motors. They all take up the same amount of space under the hood from 273 to 360. They are all basically the same motor and take the same basic parts. I put absolutely no value into a forged crank as opposed to a cast as I've never seen either one of them broken. Unless someone has done something extremely stupid or in a few cases some of those Eagle 4-inch cranks. They probably stopped making them not only because of expense that because they weren't necessary. Especially anything near a stock application. I'm not trying to suggest that you build a drag motor by the way I'm just trying to get the best bang for the bucks. Sometimes people will say even a big block in a truck gets better gas mileage because it doesn't have to work as hard for the same amount of gas?