Not sure about Toyota's but with a Opel Corsa Lite for example you'd get the ABS from a Corsa C, but it costs a lot and doesn't help as much as just putting in the non-abs SuperBoss brakes, which are basically just discs front and rear that went into the Opel Kadett 16V S, makes a HUGE difference, feels like you're about to fly out the window each time you break.
You may want to try something similar on your Conquest. Rear disc brakes aren't really that helpful IMHO tho, I had them in my previous Corsa (converted front and rear to SB discs), was very powerful but this time I have drums in the back with SB brakes in the front, still stops very quickly.
Oh and depending on the size of the brakes you'll need bigger rims, I can't go lower than 15" for example, so that's something to keep in mind.