Yes the 4 hole spacer would be better. It should help your carb. pull a better signal down in the low rpm's. You will have better off line performace without sacrificing your top end.
If you decide to get a new one go phenolic it will insulate your carb. from your engine heat, which can give you a few extra horses.
It sounds like a square bore carb. and intake. Are the holes equal sizes?
You can ask some more question I'll answer what I can, my carb. experience is limited.

 

Y es I have seen the plastic material spacer..and the wooden one..

Not sure which one I want to run,But Im switching to 4 hole spacer..


NOW is it safe to run a nitriuos plate under or ontop of the spacer?

 

I'm also planning to run nitrous with my car. The first thing I did was get rid of my dual plane intake and 4 hole spacer, and replaced it with a single plane and open spacer. I know some people run it with a dual plane, but if you think about how the wet system works I think some fuel would puddle on the inside walls of the intake. Scares me to think of a lean condition because of lost fuel in the plenum are. I may be wrong, but I like to be safe.
You said you are running an intake with 4 holes. I suggest finding someone who has done this or calling NOS (or equiv.) technical support and see what they suggest.

I guess if you are going to run direct port nos you can disregard what I just said.

 

I have run both square bore(4 holes same size) and an open spacer and the open spacer on a rotory runs like shit. I have read that useing a spacer with the rotors seperated but prim and sec open is supposed to run better wot? I have no experience on that one.