71 Duster Dyno

Looking at your graph, it's clear to see that you would want to shift at 200, to come in at 200kph x .73(the tranny spit) = 146
Well with 3.73s and 24.5 tall tires. 200 would be 6350rpm. So that could be rounded either way;6300/6400. And the power peak right around 175, maths out to around 5550rpm.
Ouch on those 60fts.A decent 60ft,and upping the shift rpm, plus a bit of shift technique,and you will be in the mid 12s easy.
You will be cooking in no time.

With the oiling mods I did, my 360 goes 7000plus any time. And it goes there a lot! Just because it can. And it sounds so awesome.

You are not running a spool are you? If you are, the tires have to be aired up the same and it's very important that you get a 4-wheel alignment. If your running tire circumferences(rollout) are not well matched, or the thrust angle is off, the rear will try to steer the car;which you will perceive as a wiggle back there at slower speeds.IDK at 150kph,cuz I've never had that problem.I can imagine the rear steering in one direction, which you would correct for. The rear would then unload one side, and the car would immediately dart off to the other side;which you would again correct for with steering wheel input.Would this sawing on the steering wheel produce a "sway"? IDK. I'm imagining.But I have run a spool on the street. And this is the exact reason I don't anymore.The correctly set up SG, I like much better; I don't even know it's back there most of the time.
The same can be said for a suregrip that has been set up too tight.