Yes, the four existing fan attaching holes are used to attach the bolt-on pulley. I face off the front of the pulley hub the thickness of the add-on pulley so there's no change in the position of the belt. I usually use a 2-groove pulley for a Ford 302 V8 and bore its center hole and slot the mounting holes to fit the hub of the 216 pump.
Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!