To confuse you a bit more a 440 manifold will not fit a 383, but a 383 manifold can be made to fit a 440...with some adaptor plates!
An RB (440) manifold will fit on a B (383) motor if you use the MP stage 6 heads.
With stock heads you're limited to a standard 383-400 intake manifold. Generally, the 69-70 manifolds offer the best performance and are the most desirable. If you're looking for an upgrade that looks stock, the edelbrock dp4b is an excellent street manifold made of aluminum and can be painted to look "factory". These were sold over the counter years ago by Mopar under the "direct connection" performance program which was subsequently replaced by Mopar Performance. I've seen a few examples of the dp4b that even had a Direct Connection part # cast onto the manifold.
Check E-bay, swap meets etc....because these are no longer in production.You should be able to get one for $100.00 or less if you're so inclined.
Ron