I wonder if the heads were flowed with the intake manifold attached.
I have seen where this can change the lift point and severity of the flow numbers backing up.

Also, testing at a higher pressure can also be revealing.

We all have our own way of doing things, but I think I'd just try and make it so the heads didn't drop off quite as bad, and run a more traditional cam.

Also, the flat tappet dwell cam option would obviously be a way cheaper approach to at least "test the theory".