GM You can weld a piece of 1/4 x 1 stock to the existing mount running full length of the block mating surface as long as you need then one hole will go through the bracket and the new plate and the other hole will be in the new plate only . then select the proper length bolts and lock washers to fasten it to block. If you don't have a welder go to front hole in bracket that you don't need and drill through new extension plate then drill a taper in the new plate to recess a flat head bolt and install a 5/16 flat head bolt through new plate and bracket then bolt on as above.


Been there, Done that, Hope to live long enough to do it again.
Big Bill
I.I.# 4698