Sorry Matthew, I haven't read through this thread yet, but just got your PM. Let me start by saying that I've done basically two L28 builds. Two with L24 crankshafts and rods and two with L28 crankshafts and rods. All four engines have the F54 blocks bored .040 over with Nissan or LTM P79 flat top pistons and SU's....none have headers. All four engines have P79 heads (same head as P90 head except P79 has liners) shaved .080 then shimmed up (valve springs and towers) .080 to keep chain height and geometry straight. The engines with the L28 cranks (to the best I've been able to determine) give you close to 10:1 compression ratio.....the L24 crank and rods will give you about 9.3:1 compression ratio. If you don't shave and shim the P 90 head, you're shooting yourself in the foot IMO. The N 42 head would probably be a better choice (I've never used the N42 head, so can't comment on engine knock.....mine have "0" knock....ever) because of the higher CR, but the P79 and P 90 is a more modern combustion chamber. All four engines use Isky reground Stage III cams (I wouldn't use anything less....they are fantastic) and valve springs. The rockers will geometry correctly using between .150 and .180 inch valve lash pads. These engines are very quick (not brutal), and very streetable and a blast to drive. Not sure which is my favorite, but the L28 crank is done at 5500 rpms (as far as power) and the L24 seems to go another 1000 rpms to max power (by the seat of the pants not yet dynoed the L24 crank engines). Both push 170 hp at the wheels (200 hp at the crank). These set ups were recommended to me by my Z expert friend the Z Doc who is no longer with us, but I always consulted with him (He built the heads, I built the rest). I don't have any other experience with Datsun modded engines although I think I might build a stroker engine since I recently acquired a diesel crank (If I do, I'll be seeking advice from someone on this forum who can help me with that build). If either of these engines interest you, I can certainly help you with your build, and will answer any questions you may have. Both engines are awesome......I love each equally. Good Luck and let me know if I can help. BTW ....if you want to hear that engine, go to my profile....go to topics and check the youtube video in "Me and Eiji head to head". He turned a 14.30 quarter mile and mine was 14.85 (he had 100 more hp)
Guy