alternator bracket?

i have a 70 rb 440, with a alum water pump housing, was on there when i got it, anyway it has a alt bracket thats used for an ac car. i bought a alt bracket kit for a non ac car, and the triangle mounting hole at one corner is too short, looks like it needed to be longer, do i buy the right one or add a piece to make it fit, looks like everything else will work...must be the water pump housing that is different....