I hope you understand clearly that the ports I'm recommending are not forward slanted as if drilled with a straight drill but are drilled with single flute 60 degree included angle champher drills, with the hole punched in square to the bores length, and on centerline. So the port is tiny where it breaks through the barrel, but wide at the top, with the hole tapering backward and sideways the same amount as forward. The reason it works is because gasses moving forward at extreme velocity impact the forward surface and back to about the halfway point, imparting forward thrust against only the forward half of the port. So only a small part of the gasses are diverted, and they don't blast sideways to increase blast, but at a 30 deg angle forward, which throws up a screen to push some of the muzzle blast forward, which is what causes the reduction in muzzle blast.
Think on the principles laid out above and you'll realize why I say to start the ports a few inches back from the muzzle. We want the port jets to preceed the muzzle blast, and also want them to act as a jet for a longer period of time than if placed very close to the muzzle.
I haven't tried it, but believe that if two ports were drilled in, say, a 6 inch revolver barrel, about one inch forward of the frame, one on each side of vertical centerline at about 30 degs, the recoil would be reduced probably more than with 8 holes placed forward, starting just behind the front sight ramp. That's just a notion I have but never tried, and a part of that notion is that with the far greater chamber pressure at the beginning of the barrel, blast might increase. Just guessing and pondering. You see, when I finally found what worked so well, I immediately quit ruining barrels to try new ideas!
I believe I mentioned in the post on this matter, that the front sight is constantly blackened, with no sheen or shine, by the powder blast, a point which I really liked.
All other ports which I'm aware of impart near equal force against all faces of the port, and derive their recoil reduction at the cost of atomic type blast to the shooter, and by diverting muzzle blast sideways to prevent it's jet propulsion backward.