"is the 261 that much better than the 235? . .
. . .what is the precission bearing vs standard"
The 261 is noticeably more powerful than a 235 - to most people, that makes the 261 better.
Prior to the implementation of precision insert rod bearings in all engines, all 216 engines and most 1953 and earlier 235 engines had babbitted rods (no insert/removable bearing).
