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

3.23 rear diff, auto 727, edelbrock AVS2 800 cfm, edelbrock performer RPM, flat tappet.

That combination of parts, along with the shorty tri-y’s, isn’t really beckoning for a cam that needs to run over 6K.

Sure, you could overcam it a bit, and then crutch it up with a loose converter....... if one “had to” regularly run it over 6k.

If 6k+ capability is truly the goal, you should just step right up to a solid lifter cam.
With what is out there for hyd lifters these days, I def wouldn’t assume they’ll be up to the task.