Non-vtec heads use a different manifold than the vtec heads. You'll have to get an aftermarket manifold for the B20A/B20B or B18A/B18B non-vtec engines.
Example:http://store.skunk2.com/engine-tuning/p ... d-571.html
B16A and B18C (type-r) manifolds require some modification to fit but it can be done. Would require removing the engine from the car since you'll have to weld the water ports (from head to manifold) shut on the engine since the B16/B18 manifolds don't accomodate them.
The B18C GSR manifold is different to all the others and wouldn't work because the intake ports on the head are aligned differently afaik.
Keep in mind that the special silver block on top of the stock manifold creates more low and mid end power, which you'll lose if you change the stock manifold.
Are you upgrading the engine in any other way? What's the reason for upgrading the manifold? Aftermarket cams etc? If not, I recommend that you keep the stock manifold.