I know that you can get these kind of numbers out of a set of 416 heads but did you happen to see who did the head work on the ones you posted. Meaux Racing ain't no joke, they would be in the top 5% of head porters. You won't likely get the same kind of numbers out of the average performance shop. Then take into account the extra 5ish% you will loose going from a 4.00 bore plate to a 3.905" bore plate. 225cfm at 500" - 5% would equal 213cfm at .500". When I gave you the estimate of 205-210cfm @ .500" that is an extremely realistic number.
These heads from the factory are only pushing around 170-180cfm @ .500" and when you do a mold port/ valve job you can expect to gain about 8-12% in flow. Given these numbers a mild port/ valve job on these heads would get you about 190-200cfm. With the 3.905 bore you should be mildly happy with around 205-210 @.500".
It takes a lot to make good power out of a small bore motor, this is why you don't see many people using these old 265, 283, 305, and 307's. If someone has used them it is usually just for a stock rebuild or for a very mild performance build. I still think that you may make around 320 maybe 330 hp and making that out of a 283 ain't bad at all