IMO, if you replaced Brads Victor heads with a set of 300cfm RPM heads, milled for equal compression, and left everything else the same, the motor would have made way less power.

Additionally, in "engine contest" trim, there would certainly be some more power available from that combo.
More aggressive cam, more rigid rocker arms, ported intake manifold, gas ported pistons, lower tension ring pack, 4500 carb on an HVH SS/adapter...... It easily would have made solidly over 700hp.

When the RPM heads first came out I built a 448 that was very comparable to Brads 452(same cr, similar cam).
I ported the heads to flow in the 300cfm range, and tested them on the motor with a few different intake and carb combos.
At that point, the best intake/carb combo i tried was the Weiand TR with 2 x 650 Demon carbs on it. That made around 595tq and not quite 640hp.
The next closest single carb test was around 625hp, with a similar drop in tq.

Brads Victor combo made 684hp/605tq with an old school HP950 Holley on it(1.375 venturi), which resulted in the motor using 20cfm less air than when the bigger carbs were being run.
Had the bigger carbs been better optimized for the motor, I have to believe some benefit could have been gleaned from that extra 20cfm of air.

With the current crop of std port offerings available, for me the real litmus test would be how much difference in power there would be if you pulled the Victors off Brads motor and plopped a set of ootb TF240's on it.
If it made within 10-15hp of the Victors, then that would be a good argument against the viability of the std port version of those heads, at least at that power level.
It would be a fun test.

The nuts and bolts of this particular test is that Brad replaced his ported std port Stage 6's and flat tappet cam with the std port Victors and a roller cam and picked up 20ft/lbs and 60hp.

There are a few things I don't really care for in how the Victors are made, but I'd say the biggest "problem" with the std port version for me is the they are cast with the bowls .300 smaller in diameter than they should be.
If they had the bowls sized correctly to begin with(sort of like the original version was), then I would feel better about recommending them for the hot street applications where a high flowing std port head can work.

As they are now though, they're too labor intensive to be cost effective.

I wouldn't mind doing a "low effort" type job with some Pro Comp "Victors" at some point though(since those don't have the ridiculously undersized bowls).