Bob,
You corrected the wrong way. And I had 10000 instead of 10700 rpm.

12A  Pports can do 310 HP at 10,700 RPM at .667

If the .667 is BSFC then start with that

Density of air at sea level 15C = .0765 lbs/cf air/fuel = 12

.667 bsfc x 310hp is 206.77 lbs/hr fuel

206.77lbs x 12 = 2481.24 lbs/hr air

2481.24 lbs/hr  /  60min/hr = 41.354 lbs/min

(41.354 lbs/min)  / (.0765 lbs/cf) * (1728 ci/cf) = 93411 ci /min

(934113ci/min) / (10700 rev/min) = 87.30 ci/rev

1200cc / (2.54cm * 2.54cm * 2.54cm)/ci = 73.22 ci volume

87.30 ci/rev / 73.22 ci/rev = 1.192 =119% VE

Blake