A few thoughts ...
Consider increasing Vr speed to the performance limited gross weight rotation speed, not to exceed actual gross weight Vr + 20 knots.
In shear/gusting conditions, a bit extra is for pilot comfort, improved climb gradient capability, and increased stall margins. What you are doing is trading the longer runway weight capability to achieve a modified overspeed takeoff. Overspeed increase generally is limited to around 20 kts to get the benefit of the improved climb gradient without too much distance increase .. above this, the gradient improvement is likely to taper off progressively while the distance increase becomes comparatively dramatic. Keep in mind that the climb gradient graph is a bit like an upturned teacup.
Set V speeds for the actual gross weight.
You're looking at a dynamic met situation with a goodly chance that things might cause you to need to rotate earlier than at the planned overspeed Vr. Bugging the base speeds means you have the minimum speed schedule for the weights right there in front of you should things get untidy.
Rotate at the adjusted (higher) rotation speed.
ie, if things go fine, you will do something akin to an overspeed takeoff
If windshear is encountered at or beyond the actual gross weight Vr, do not attempt to accelerate to the increased Vr but rotate without hesitation
To do otherwise puts you in the lap of the Gods as you have no quantitative idea of what the real acceleration is ...
Avoid rotation during a gust. If a gust is experienced near VR, as indicated by stagnant airspeed or rapid airspeed acceleration, momentarily delay rotation
Again, you don't have any idea quite what the weather gods might be doing for the short term. On the other hand, if you have pushed it up to a limiting overspeed case, one wouldn't want to delay to the extent where you might go off the end of the runway. However, keep in mind that, if you don't lose a motor, then you have a distance factor on top of the expected certification AEO distance so, probably, it's not all bad.
... and if you encounter the event you use the new speed of 158 kts?
Not quite. You're planning and intending on using the higher speed .. UNLESS things get messy.
... consider increasing VR speed to perf limited gross weight"? What does this mean in plain english????
As above, in effect you are now running with an overspeed schedule for the continued case while maintaining the lower scheduled V1 for the reject case.