Thanks for chiming in, ToxicGumbo!
Ubuntu 22 is too much of a hassle. I went back to 17; which works like a charm.
Emstudio compiled straight away.
Almost about to firing up the soldering station.
Voltage regulators and 12V/GND first; so I can at least set up comms with the Jaguar.
Still trying to figure out which resistors to use on the voltage divider for RPM input.
Mostly documenting this for myself...

I have the lovely 60-2 trigger wheel. AFAIK there's no support for a 2nd rpm input; so I'll just equip the RPM0 input.
FWIW I think this is a VR input; so I'll leave R22 empty.
From the components that Andy kindly provided, I will be using the 10k resistors on R18 and R19. 5.1K for R23.

(omg. these labels clearly state 2014, don't they ...)
R83 is a 1K resistor:

Andy wrote 'For hall/digital rpm inputs' on the bag; but I still need this R83 1K resistor, don't I ?