I had a d21 with Z16 carb in. Got a Z22 and some cheap KA24DE pistons & rings. The coating was removed from the dished piston tops when cutting them down 1.4 mm for clearance . We floated the small end pins in the Z22 rods, & overbored the cylinders 0.078" ,decked the block and surfaced the head . I got an aluminium flange made for a Weber 36 dcnvh (12-100) synchronous carb. [ex.Maserati bi-turbo] and using a hole saw opened up the standard mount on the intake and had the new flange welded on top . A fellow fitted the flywheel into his lathe and followed my instructions removing cast from the edge behind the ring gear and from the two faces until we got down to sufficient lip to stop the ring gear at zero and weight to 12 Ib's . I was chomping at the bit to score a good cam for it also, but it ran for 18000 Km with no trouble apart from it had to be stalled when switching off once warm or it pre-ignites or compression ignites ,running on with terrifying sounds and events including running backward in a forward gear one time . Performance increase was quite impressive but it wouldn't rev over 4000 very smoothly. At low revs it pulled like a horny schoolboy although some discretion was required with throttle to prevent pinking down low. Coupled to the 4.88:1 diff ratio and being a truck it did everything I could expect of it. I have a KA24E cylinder head and was such temptation to bolt that on top but for the timing chain length and questions over the oil drains back to sump clashing with coolant passages. The bottom line is you can do the Z22 and oversize pistons from KA or Z24. Also the V6 range of Nissans has good options for pistons. (2 mm O/size) No trouble with cooling , gasket leaks or blowing. Otherwise however the L head or turbo the Z , because what you read about the restriction gets worse with cubic capacity and none of my Z's N.A. performed despite tinkering with the standard engine. I've had five with z engines, Gazelle S110 , Sylvia turbo , navara single cab flatdeck, and two crew cab wellside trucks . All went suitably but the Z22 hybrid was the pinnacle of the group as far as performance and economy goes.