there are no real diffrences between the y8 and z6 minus the intake manifold they are very similiar so my .02 is go with the z6 block i always think you should run the same block with the head. a mini me is the same as an ls/vtec its a match that works but in the long run puts excessive wear on the block. i agree with wgs dont go the cheap route do it right and you only have to do it once.

Josh