The 34 5 window has both metal and wood bows. There are two metal bows above the rear window, a light one about 5/8" wide and a heavier one about 1 1/8" or so. Both these bows have a composite tack strip attached. The heavier bow is positioned directly above the rear window, is attached on both ends and also attached to the wood rear window surround. The lighter bow is positioned forward of the heavier one and attached on each end. Note that both these bows are attached with flathead screws and nuts to the metal "flange" that surrounds the quarter window. The rear of the headliner is tacked to the heavier metal bow. The tacks will be covered by the panel that later surrounds the rear window. As for the front of the headliner there is a composite tack strip attached to the body (behind the header panel). It looks like twisted paper and is most likely degraded. That can be removed and replaced with a strip of wood.
In addition, I would avoid trying to staple to the metal bows. Wood bows ok, but the tack strip composite is only about 3/16" thick. Select an upholstery tack that is about a 1/16" longer than the tack strip is thick. The function is that when a tack is driven into the tack strip it hits the metal under it and the tip bends over and holds fast. Anyone who has had to pull these suckers out can attest to this.
34 Fordy, If you send me a PM with your cell number I can text pictures of these metal bows installed. Not sure how to post them here.