Long rods...or, more accurately, a higher R/S ratio compared to a smaller one in the same engine/deck height.....can, at times, INCREASE the tendency for detonation, because the piston spends a longer time (dwell time) at or near TDC, due to the rod angularity.
An interesting example of this can be found in the pre-2006 Engine Masters PHR contests, which were basically exercises in controlling (short-term)detonation. Jon Kaase, a two-time winner, & of IHRA fame, used extremely short rods. This was to, in his words, "yank the piston away from TDC as fast as possible" in an effort to minimize detonation. Then you get into a tradeoff between having an increased compression height (& greater piston top strength, possibly, to endure), vs. a relatively heavy piston.
His solution was to use very short (comparatively) rods, an exaggerated stroke, reasonably short compression height, & to sleeve down the bores (on his BBF) to keep CI within contest limits. He also physically moved the valves & plugs in the chamber to reduce shrouding & lessen flame front distance. This kind of effort is the primary reason why they altered the rules for the '06 contest....& one reason why the Cleveland hybrids dominated this year.
If I had to make a guess, I'd say that it sounds like you paid proper attention to deck height, & possibly the fuel/ignition curves...combined with the Y wedge chamber design & smaller bore diameter....& maybe cam overlap...rather than the rod length one way or the other.
Either way, it works...so it's all good!
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