Nice graph crazycage.
Was the HP at the wheels or converted to crankshaft power?

On the head porting front - I had a race shop port my cvh head with the larger Burtons
stainless valves. The result was quite dissapointing when flow bench tested. A 15 cfm gain from stock ports and valves. (15 cfm at 28" depression) Still this 15 cfm would result in a 30 hp potential gain at 1 bar boost.

I then took it upon myself to carefully develop the head. Just enlarging the port and fitting the larger Burtons valves yielded 15 cfm (@28") peak flow. My brother had just purchased his own Superflow600 bench, and we decided to rework the cvh head.
We started with 2 standard castings, so we had 8 ports to experiment with. careful attention to port cross sectional area, and correct port taper we discovered much more flow. We did not even go to the larger valve sizes, but remained at 42mm.
The port size we kept 1 to 2mm smaller than the inlet gasket size to keep velocity high.
The cvh port being a swirl port requires some knowledge of what and where to remove material - a tricky port to properly modify.
In the end we attained 193 cfm @ 28" and 0.450" valve lift using factory 42mm valves.
This is a gain of 43 cfm from stock unmodified casting. Potential for an 80 hp gain at 1 bar boost level.

Cheers All