440 Camshaft recommendations for up to 6-6,500 rpm?

With that gear I'd definitely go with the .528 purple solid flat tappet Andy F mentioned
In the old days the Mopar 0.528 would've been my first choice also. These days Mopar charges a lot for that cam and the quality is a little suspect. So if it was me I'd try to find a shelf cam from a trusted source that had similar specs. The 0.528 had a wide 112 lobe center (which is out of favor with most people) so that is the rub if buying a shelf cam. Most shelf cams are ground on 108 for better peak performance.