How close to the sensor did you start your shielded cable? Where did you ground the shielding? On my Bosch distributor, there's a small rectangular two pin plug on the side for the sensor connection. The shielded cable starts right at the plug. Only earth one end of the braid, just find a good eart...

I'm not sure that will be doing much, the gaps between each turn would need to be just about zero. Jaycar sell a couple of different shielded audio cables by the metre - I think this is one of the types I've used with reluctor sensors in the past with great results. I don't suppose you happen to hav...

Is that proper shielded twin conductor cable, or was that a DIY job?

The way it goes nuts as soon as you hit the key makes me think it's not the alternator - it's happening before the engine gets a chance to start rotating. It could be a bad starter causing the RFI, but that wouldn't continue after you got it running... Your wiring harness isn't running too close to ...

That log shows RPM hitting 9600 the instant you hit the starter, then jumping between 200 and 3000 roughly twice a second.
Maybe try disconnecting the injectors and leave the coil killswitch on, and grab another log to see if the interference is caused by the ignition system?

Seeing as you don't need to bore too deep, you don't need to worry about clearancing the neck.
Just grind a profile like below on an old drill bit/broken tap/file etc - or you could probably even get away with mild steel for light aluminium boring...

You can make small boring bars out of broken drill bits or any other HSS rod - it takes a lot of grinding to neck down for clearance though. Or, indexable carbide boring bars with a few inserts are about $30 on ebay - they're chinesium crap, but they cut so much better than any HSS tool I've ever gr...

Bit of an update on off the shelf programmer options - at some point in the last few years, support for these chips was added to the TL866 programmer . It's there in MiniPro v6.60 / firmware 3.2.80 which I think are pretty old versions anyway, and I can confirm it reads and writes these perfectly. (...

I can't tell you if that programmer would do the job or not, I recall that the programmers that others were using didn't support this chip's pinout so needed to use the ICSP port and a bunch of jumper wires or something. It was a long time ago... I managed to find my spare chips, programmer and soft...

I wasn't planning on pulling the chip out of the cluster to do it - the tool I made just plugs into the cluster's programming port. here's a quick demo https://youtu.be/amYQ7H3FrKo I think I've still got a couple of spare CAT2444 chips here somewhere. I'll have a look for them tomorrow. What's the '...