This question boils down to which is better: A bunch of stroke or a mix of bore and stroke? For this example build the two engines would have the same compression, cam specs, heads....The 348 with a 4 inch stroke should have plenty of low end grunt. The 427 in a Z11 has just a little more bore/stroke over a factory 409. I would think they would have little difference between the two but maybe there is something I'm not considering. The rotating mass inside the engines should be similar but one clearly has smaller pistons and a bigger stroke. The other has larger pistons and a little stroke. Just pondering why Icon decided to settle on the 427 number for their 4 inch stroke pistons for the 348. This is as much a 348 question as it is a Z11 427 question.