Water pump difference

If the AC is out of a 64 thru 70?? then it should have been setup for a cast iron water pump with drivers side inlet.

The 71??? And later aluminum water pump uses the passanger side inlet

The pump determines which timing cover is used and which balancer as the timing marks are passanger side for the cast iron years and drivers for aluminum years.

As for AC brackets, that will be dependent on the year they were designed for (AL or CI water pump) regardless of water pump design.

As I understand it the attachment bosses are a different height AL to CI.