http://forum.ratsun.net/showthread.php?t=1011
Specifically, "Big Bore 2.3L KA24 pistons into a bored Z20/Z22/L20B block. The small 2.8cc dish area of the KA24 pistons helps to preserve compression ratio even with the low piston deck height. Compression ratio with a open chambered U67 head is 9.9:1 or use dished Z24 pistons and peanut chambered head for 8.9:1 compression ratio. Parts: Z22 crank, KA24 pistons, Z22S/ L20B rods in a +2mm bored Z22 block or +4mm Z20/L20B block. s/2+r+p= 92/2+145.9+34.0= 225.9 mm piston deck height: -1.55mm below deck "
f your going to take the Z22 motor and put KA24 pistons in it be sure you get your block from a Z22S ('81-'82 720 pickup). The reason is HUGE! The water jackets on these year motors were further away allowing for the larger bore. Any other ones will give you overheating problems. One more thing. LOOK for the block to be cracked out at the middle stud hole for the head. People tend to bolt the head back down without tapping out and cleaning it. The head bolt then bottoms out and cracks the block right where the water jacket is....bad news....but you must look. If you get lucky you'll find one. I bought my block off of a guy who bought, I think 5 before he found a good one.