I'm a Ford guy through and through, not only because of the various Ford vehicles that are just awesome, but because of some of the features of the Ford engine. They are more detail intensive to build than a Chevy though, but I think some of the block/head designs are superior (not necessarily in performance, but in just how well they were thought out).
For instance...
1. On a Ford, the distributor is in the front, which just so happens to be the end of the engine where you're looking at the harmonic balancer with the timing light.
2. On a Ford, when you go to a roller cam, you can use the same thrust plate, timing cover, etc, and there's no voodoo to setting them up. On a Chevy, you have to run a lock plate, button, and sometimes a reinforced timing cover so it doesn't flex when the button rides on it.
3. LS engines copied the Ford Cleveland head design, down to the bore spacing and general port layout. ;-)
4.
Oil pump pickups have to be pressed in, then welded. Fords bolt to the pump, or screw into the pump with a pipe thread.
With that being said, I've been able to build both Ford & Chevy engines with the same cubic inches, same head flow, same cam specs, compression, etc., and for the most part, if all the specs match, the engines make pretty much the same amount of power.
And when it comes down to it, and you think about it, engines don't know what brand they are, they just know that they have air and fuel coming in, and they make it explode. If head flow is the same, cam specs are the same, etc., they should be very similar to each other.
I built a 427 rat for a guy's '68 Vette convertible resto, reused the factory block and heads, went to a hydraulic roller with about 234 degrees duration, .600" lift, good flowing intake, around 10:1 compression, and it made around 465 hp.
I also built a 427 FE a few months back, and although we used Edelbrock heads, we used them as cast. Cam was a solid flat tappet at 240 degrees duration (you lose a little duration to lash on a solid cam though), compression ratio was about 10:1, good flowing intake, etc., and it made 470 hp.
I've also built a 482 ci rat that made around 550-560 hp if I remember correctly, and it so turns out that a lot of my 482 inch FE's with moderately ported Edelbrocks also hit around that number.