In the 60s, when representatives from Chevrolet were asked why they put a 454 in the 'Vette instead of the 427, they said they bored it out to "save weight."
Obviously, the weight savings is insignificant ... and the extra displacement (I think you bored it .040"?) is just a few cubic inches ... but if that is 1% then you will probably be close to 1% more power and 1% more fuel consumption.
The increase in pep was probably better compression, not increased displacement.