I've done some of this so I'm interested to see what others post.
In Logic you can select multiple parts and then <right-click> and bring up the attributes. At that point you can change any common attributes to a single value (Geometry.Height = 3.4mm).
In the Library Manager, use the 'Export' button instead of the 'List to File' button. Then you can make changes to the ASCII file and import the changes back in.
You can also use the Attribute Manager (<Edit><Attribute Manager...>) to change things specifically for a given schematic. Note that this is different than the Attribute Manager in the Library Manager dialog that allows you to change attributes in the Library.
Great help, I appreciate the feedback! I should've known the first method since I use the "select all" components when saving parts to PCB p/n specific library...