magnum heads on a 416 stroker

You need the proper style and length pushrods and lifters that can oil through the pushrod. Though most lifters for the MoPars are this way now, actual proper lifters for most MoPars are not that way from the factory.

Your cam question, what cam, is a cam that fit the intended use of the build. It can be any style cam.
But! Keep in mind, if you use an LA cam, the lift must be divided by the LA rocker ratio (1.5) and then multiplied by the magnum ratio (1.6) for the new lift.

You ten must get the proper springs for the new higher lifting cam and check clearances. AKA, no vale spring bind.

Also keep in mind that if you use a Magnum engine cam, it does not have a long snout for the use of a fuel pump eccentric.

If it were I doing this, it would be ether the RHS style head (seek "Magnumopar" here@ FABO)
or a ported Edelbrock Magnum head. (Hughesengines.com)