Basically any 727 selector linkages will line up for the A518 what you need is switches to engage the overdrive and lockup convertor as they were controlled by a computor. The biggest problem is getting the kick-down linkage right, it is adjustable.
However there are a few kits around that can be fitted to make the overdrive and lockup work automatically.
Check out the sticky thread about fitting a A518, it is very simple.