The wiring loom can be purchased from gary rs breakers prob for peanuts.
sensors are a different ball game at 120 quid a corner for a sierra which is what you need.
any adaption of plugs for sensor will result in a non working system as they can be a pain.
If you can find a 4x4 sierra or a late ghìa it will have the rings on the rear shafts which you can machine off. The front hubs off a sierra again machine off and fit on the back of capri hub assuming your discs are now on the face. Machine off 4 original disc mounting points and mount ring fab a bracket from caliper bolts for sensor job done.
Same principle for rears but remove half shaft and turn down between halfshaft plate and hub to fit ring.

its a lot of work really and i did think about doing in in my cossied cortina many years ago but the brakes where fine and worked well.

Abs is not going to stop the ass end coming round on a capri been there done that.