#920 vs. #675 Heads "Compression vs. Cylinder Flow"

Which Cylinder Head Performs Better,

#2658920 {1966 and 1967 '273'}
Closed-Chamber @ 57.3 CC's

#2843675 {1968 '273' ~ 1968 thru 1974 '318'}
Open-Chamber @ 60.6 CC's

On the 'bench' both Cylinder Head Ports flow near identical.

But, a true test, on a running Power-Plant.

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No other modifications, just stock Valves {1.78" Intake and 1.50" Exhaust}.

Does the better Compression of the #920 Head {+.35}, outperform
the better Cylinder Flowing #675 Head which has less Valve Shrouding.

Were going to try this 'test' on a 'restored' 1967 Barracuda '273 Commando',
~ 'stock' with factory cast 10.5-1 Pistons {+.040" oversize}.

Everything else is 'stock'. {ie; Camshaft, Carburetor, Intake and Exhaust}