I have never heard of either of those engines being swapped into a 280ZX. I would imagine the ka24de will have more info when it comes to swapping it into a Gen 1 Z so that info could help. But I have never heard of anyone using a 4.9L in any generation of a Z. Doesnt mean it cant be done, just means you'll have to do more test fitting than say a 5.0L swap.
Hopefully if someone has done either one of those swaps in a 280ZX they will speak up and help you out!
Guy