How much height do you have to work with? Standard crossflow rad's are 19" tall then whatever width you can fit. I've been using Griffin aluminum rad's in most of my projects for years. New at Summit for around $180 typically. I was checking on
www.speedwaymotors.com yesterday in their clearance stuff and noticed a nice aluminum rad 31x19 I think it was for $120. I'm assuming you will have a height issue with the frame so high so I can't help answer your question any closer than that, but the aluminum rad's have a much thicker tube so a 2 row with 1" tubes will cool better than the old 4 core rad's (with 1/2" tubes) the trucks may have come with from GM. My truck isn't Z'd so I have planty of room for any rad I want to run. I plan to use one of these crossflow units and fab the mounts for it.