Hi DD,
I think it is to provide additional stiffness and support of the starter plate/flywheel cover, but the starter is well supported anyway with the through bolts. Seems like you could run without the bracket. Maybe a few starts by a helper while you're looking at the starter and plate.
Vanpelts page on this is good:
http://www.vanpeltsales.com/FH_web/f...s-adapters.htm
Glenn