[Dwight]

the 427 is a large bore short stroke motor (4.23" bore x 3.78" stroke) made to produce horsepower at high rpms. By 1965 Ford had a 427 motor that could run 7500 rpms for 24 hours.
The 428 (4.13" bore x 3.98" stroke) is a low rpm torque motor for the street.

Both can make the same horsepower.
Coach Mike has a Keith Craft 428 stroked to 461 making 601 hp & 619 tq at the flywheel.
Mike Lainhart has a '65 427 s.o. that Keith Craft stroked to 487 that makes 619 hp & 632 tq at the flywheel.

One is 9:0 to 1 and the other is 9:5 to 1 compression.
Both are very street-able and great Cobra motors. Push the gas pedal to the floor and hang on!
With the heads and cams available today you can have a great street motor with a lot of hp. Just tell your motor builder what you want.
Dwight