To really see a compression bump do the "Cadillac" stroker modification on a 261 which takes the displacement up to about 292. That makes an 848 equipped engine a premium fuel only application, even with a relatively radical cam profile. I'm considering doing that to the 261 I've got stashed away. One interesting bit of trivia is that the 261 uses the same diameter wrist pin as a small block V8- - - -.927". That might open up all sorts of interesting piston combinations, including some of the domed pistons made for the 265's, with the same bore size as a 261. Some of the custom piston makers like Jahns, Keith Black, or ForgedTrue used to be willing to make a one-off set of pistons with special compression heights, dome shapes, etc. The stroker uses a 292 rod with a smaller-diameter big end bearing. which also has the .927 wrist pin, IIRC.
Jerry
