I have a 71 Challenger and just toke out a 340 and put in a 440. The 440 has a Edelbrock RPM intake and it looks very close to the height of the hood. The hood is a R/T hood. My question is is this gonna work before I put the hood back on?

No actual RT experience but what I'd do (& you may have done this from your descrip) is measure across the carb air cleaner side to side & get a dimention of the carb height to the "grooves" on the fenders on the sides where the hood sets down into then get a measurement on the hood, the "height" of the bottom of the sides (which contact the aforementioned fender grooves) compared to the inside metal where the air cleaner would touch then compare that to your first fender dimention. That might get you pretty close. Other than that if no one replies I'd mockup and see what you get and a drop base air cleaner will help tho you need a certain amt of filtering element sq in of area and the top lid cannot be too close to the carb bowl vent (no specific numbers on either of those last two but the info is out there)

I don't think that will work as it is without a drop base air cleaner of some sort. Ive seen talk on this site about good drop base setups. My 71 440 Challenger has an RT hood. It has a stock 4 barrel intake and a vacuum secondary Holley 750. The wing nut gets just barely into the hood if I don't use a real short one or take material off. I have a 3 inch " normal height " air cleaner. I think the RPM intake is a little higher than my intake. We'll probably both end up with a drop base type. Good luck !

The same combo does not fit in my 68 Charger.
Changing to a TorkerII intake for the car inspection.
After the inspection I'll change to a tunnelram and fiberglas hood with a scoop :-)

We have these stupid rules that we have to inspect our old cars every 2 year.