Three local LEA's have issued the G34/G35 for many years and have no issues with any of them shooting high. Sounds like a sight issue rather than a pistol issue.
The Zev 2# spring is basically the same as 4# springs sold by everyone else but them producing a 2# trigger pull with the complete kit is wishful thinking.
The Wolff 4.5# springs will increase the trigger pull approximately 5oz. over the 4# springs but they are much more reliable when using the OEM firing pin. I change the 4.5# springs at 10,000 rounds and have not encountered any light strikes. YMMV.
Factory FPS and TS are matched at 5.5#. A stronger TS and a much weaker FPS can upset that balance and cause reset issues in Gen 4 Glocks.
If you use a 6# TS and a 4# FPS the TS is now 50% stronger than the FPS and they were originally balanced at 5.5#.
I started phasing out all my Gen 3 Glocks when the first Gen 4 was available and the only Gen 3 Glock I now own is a NIB G17 Anniversary Edition signed by Gaston Glock.
I have fired more than 100,000 rounds through Gen 4 Glocks with Zero Blisters. Maybe you need a new Armorer. A litttle emery cloth will fix that issue in a few minutes.