I suggest you get a scope on the live wire with a current shunt and watch the waveform rather than assuming the current is directly proportional to the revs. You'll see some massive peaks and strange waveforms as the coil charges and revs change.
Where have you seen the information that limiting the current to the coil will act as a rev limiter or is this based on some basic tests with a multimeter ?
I assume you don't like using the fuel cut method as your engine may start to run lean at high revs ?
I've been running a business desiging bespoke car electronic systems for the past ten years and haven't come across any method like this in the past. We've put in current limiting in the form of a chopper circuit on lower impedance coils so they can charge faster from a higher voltage source than they were designed for without overheating but I see absolutely no way of this working reliably for a rev limiter application.
Have a read through this document and have a look at how it all works - it may be a little more complicated than you think :
https://www.electro-tech-online.com/custompdfs/2011/11/052005_04-1.pdf