No way in the world would I trade my new 4.990 rough bored World cast iron Hemi block for a Indy aluminum block unless I was planning on using a blower or turbo and I was wanting to be able to repair the aluminum block easier after it broke racing it The iron or steel sleeves in aluminum blocks expand at a different rate than the aluminum block does resulting in uneven ring seal causing higher crankcase pressures at WOT It's your choice. BTW, why do you think the other person is wanting to trade you