I've never seen anyone do this on the N/A. The reason it's so easy on the turbo is because the 280zxt & all Z31's use the same ecu plugs. You just have to cut & solder several wires. You will need the entire Z31 n/a ecu wiring & run it to all the sensors for the N/A L28... or at least cut the Z31 ecu plugs & solder them onto the 280zx n/a ecu harness.... which is about 30 wires (fun!).... and don't forget all the wire tracing to match them to the Z31 ecu (more fun!).
You WILL need the 82-83 L28ET distributor w/ the VG30 CAS "chopper wheel" as ALL Z31 ecu's use that optical pickup.
I think the reason no one has done this for the 280zx n/a is because it would be too time consuming, for little benefit. If you're going to spend all that time rewiring, go megasquirt. The reason I did the Z31T ecu swap, is because it was very simple... cut n splice a couple wires & pop in the new ecu... much less time n money than swapping to Megasquirt, but with less benefit.