Neil,
Is it possible to remake the part by machining a new piece out of a better material?
BTW, what do you have for a hobby car?
Here is a modified spindle from a 1970 camaro, I am installing C5 corvette brakes and had to move the attachment points outward for the calipers to clear those C5 rotors.
In that picture, I haven't removed the broken off backing plate bolts. They get drilled out and tapped to accept 1/2x13 grade 8 bolts for the caliper brackets.