I'm not against fixing any obvious port mismatch problems, or opening the manifold outlets as much as the pipes you're planning on using will accommodate.
But pumping abrasive slurry through exhaust manifolds doesn't seem to be a cost effective way to gain power in most of these applications.

I'd use that money somewhere that will make a difference...... Like a roller cam instead of a flat tappet.

Tony's 511 used aftermarket heads, and the port exits were likely larger than the OE manifolds, so making sure the manifolds were at least as big as the heads was a good move there(of course this assumes you can't bring yourself to running headers).