Brian:
Knowing which air grabber base you have (originally for 383 or 440, as they're different)will help answer your original question as to which manifold will help you "on my 70RR to clear air grabber". The 440 base is shorter than the 383 base because the intake and carb sits higher on the 440 than it does on the 383. I understand it is really close running a 383 air cleaner base on a stock 440 manifold so running a taller manifold and a 383 air cleaner base may result in hood clearance problems. Some of the guys here can tell you the difference in height on the 383 and 440 air cleaner bases, I'm thinking it's around 3/4 inch. RR's weren't available with a 4 bbl 440 but GTX's were, however it makes the bases hard to find (=$). I don't have a stock cast iron manifold to measure to compare to the above measurements but if you can find a manifold that is actually LOWER than the stock cast iron one by 1/2-3/4 inch you may be able to use your 383 base.
(Understand that to do this you will be giving up some top end hp by not using a better (taller) manifold design, but if you have to chose between the air grabber and the intake.....that's your decision.)

jt