One thing for sure is I would not bore a virgin 340 block! Good 340 blocks are getting harder to come by, there is no reason to shorten its life span by a needless overbore, there are plenty of 340 seasoned blocks out there if you want to overbore one. In a street motor, unless your street racing, your not going to miss those few CI the overbore would provide. Throw the stroke kit at it, and add a power booster if that is not enough for you. I would also do the EFI. I would think as time moves forward the EFI is going to be easier to tune and dial in properly. Gene