it will most likly be cheeper to just buy a set of heads that have the hole for accessories then to drill and tap them. that way you know that those hole are exacyly where they are suppossed to be. don't get me wrong,there are sone very good shops out there but why take that chance? but if the system you bought allthe stuff it might not be that much of a problem because the serpintine system uses a bracket that bolts into the lower portion of the block right beside the timing cover where the cranck sticks out as well as the bracket that bolts to the two exhaust bolts on the passeger side of the motor. just don't forget the bar that bolts onto the intake from the idler pulley.
Foot to the floor,hair back,knuckles white.