The attached two pics show 2 of the 3 brackets for '69 SB. One bracket attaches to the exh manifold. A second bracket attaches to the front of the pump and also connects to the bracket attached to the exh manifold for belt tension adjustment. There is a third bracket under the pump which doesn't show in these two pics. Hope this helps.
In your picture, you have the bracket under the pump and the bracket that attaches to the front of the pump. You need the bracket that attaches between the first exh manifold bold and the motor mount. It is available in the aftermarket.
Also, if you have a '69 Assembly Manual, look at RPO N40 in the back.