Back in the old days I was a fan of Bruce Crower's columns in Hot Rod. He discussed many topics. I found this one interesting where he built a 15.8-1 compression 350 engine and bled off cylinder pressure to a reasonable figure (see the Atkinson link above). I never saw anything else on this engine. He may have tried to market a kit for chebbies, but I'm not sure. He's working on a 6 cycle engine now Crower 6 cycle Not the easiest thing to do on a 273, but it would be a good project.

Back in the 80's I put a towing cam from Comp in my 327 Camaro/Powerglide with a Holley economaster 2 bbl and it did pretty well. Over 20 mpg on the road and the cam was torquey around town. I think the duration specs were less than stock; it ran out of steam at 4000 rpm. I would have liked to try it with a 4-speed.