can i use a cheater nitrous kit with the rpm aiir gap
 

can i use a chearter nos kit with an rpm air gap intake its a dual plane

To answer your question. Yes you can.

will it be safe at levals over 150? Will the nitrous spread out evenly? or would I be better off with a direct port kit?

I have the cheater system on my car with the standard RPM intake. (non air gap) The tech guys at NOS told me it would be fine. It's great so far up to 150. I jetted it down to 100 to start with. I can't tell you from expierence yet about the upper levels though 'cause I haven't gone over 150 with it yet.

The air gap will do fine with a 150shot. A local guy here has a 69 Chevelle with that air gap intake and he runs a 200 shot with no problems. It's good with nitrous because it gives a denser air charge.