I dont see why a AFC couldnt be used, bit rougher then getting a proper ECU, but would work. Only issue with AFC type devices is its altering the AFM reading, not the injector pulse width directly, which in turn wil change the calculated load the ECU uses which wil screw with other maps like timing, most likely pushing into load cells with more advance and thus allowing detonation, etc. In other words it would work as a bandaid solution to get it driving but id save up for a cheap link or similar. Also, the GDB ecus can be scaled to suit any injector size, but trying to wire one into an old legacy would be more time and money than its worth IMO