The Maxima head has higher compression. The Maxima uses the L24. The block has a short stroke and dished pistons so the head has very small chambers to keep compression up. When bolted onto an L28 it will make for a higher compression engine.
The Maxima head has smaller valves like a 240Z head so it is not good for high rpm performance right off the car. I suppose it is comparable to the E31 240Z head.

 

Do you know the casting number off the maxima head? Is it the n47?

 

I believe when put on with flat top pistons it will raise the compression to 10.1. We just did it on my friends 240 with a 83 lower block with stock internals. Made it a little bit faster.

 

The earlier 280Z heads will give you higher compression but with an open chamber design. Its a toss-up as to weather they are better overall for performance. If you're against head shaving then its one of only a couple ways to get higher compression.