Many thanks to Dan Wilson

Here's a brief description for install... On the older XS650 ('70,'71,'72, &'73) there's no barb on the intake manifold and no one that I know of sells an intake manifold with the barb feature while keeping the same angle as stock.  To get the carbs in sync--you have two options-- install barbs on the carbs or add them to intake guide of the head.  I opted for the carbs--- a lot easier.  So here are 5 pics and a little description for each:

My green pencil pointer showing the brass plugs on the underside of the front of the carb                                         Just a closer picture of the brass plug

A shot of carb with the brass plug drilled out--fairly easy (small bit to center hole--then bigger)               The size of the hole doesn't need changing--ready for tapping (6mmx1.0).

                                                            The barbs installed that I got from MMM (6mm) and ready for the manometer--easy breezy....