twisted minis
+1y
You don't want to use a whole Toyota spindle, it will create bump steer because of improper suspension geometry. Your best bet would be to get a 5 lug hub. I think the spindle can be machined to the same taper as a Toyota and run a Toyota hub and disc, and space the caliper correctly, then you will have no steering problems.
Or, there is a guy in Canada machining Mazda 5 lug hubs from scratch that comes with a disc that fits with the stock caliper, and provides a little extra offset.