Forging you own path can get you lost- the fact that OP is asking whoever will answer on the internet means, he does not understand. Better to spend the money on shooting classes.Though I agree the G34 doesn't need to be ported to shoot it fast, when trying to reduce muzzle flip, every little bit helps. If I were going to port a G34, I'd have it done EXACTLY like the OEM G19c. Also, I'd have the ports as close to the muzzle as possible...not so much for more fps (though it helps, some), but for more leverage. 9mm is a bit weak, so the closer to the muzzle end of the barrel, the better the ports work, and the few fps gained also aids in more pressure to the ports. The downside to ports as far forward as possible is some of that extra leverage gets from the barrel to the slide. It may disrupt cycling. You'd have to keep that area lubed with a high temp syn grease and it'll get dirty, fast. If you clean it after every range session or every couple hundred rounds, you'd be ok. If you can't find someone to do it like the G19c, but closer to the muzzle, I'd pass.
You are getting into the weeds with complexity, care and maintenance-- all for minor effect that does not compensate for poor shooting skills. The best way to have a ported Glock is to have a Glock factory ported-- then you assume that they did the necessary R&D to properly mechanically port the tool, and that the timing works-- but then you have to R&D to discover what ammo works best.