Nice XS1 (???) tank. Like you, Vince, also skeptical.
Man, I hate to do this, but would have a few concerns.
Member txxs has posted some nice pics of his Oceaniana (?) green '71 XS1F "double-striped" tank. My old parts lists show the 00-01 tank number and paint code as the '70 XS1. I have NO part/code data on the various 70-72 paints, except for the basic 3, green-single-stripe, gold-double-stripes, red-white-stripes. So, this is still a learning area for me. So, that double-striped tank, with that single-stripe 00-01 number seems odd.
Back in the '70s, I, and the Honda parts guys, had noticed some subtle differences between some Honda *as installed/delivered* body parts, versus separately-ordered spare parts. Sometimes had to explain these things to customers, usually for crash repairs. So, I wonder if there may have been a similar *variation* in Yamaha's parts stream.
Otherwise, there's a few items that caught my eye.
The underside of the tank, petcock sealing surfaces. Our new Honda tanks came with unpainted and taped-over petcock sealing surfaces, like on that NOS white police tank posted by BobbedSled. Looking closely at the original eBay pics, I could see some mysterious marks underlying the paint in those zones, as though there may have been a history of previous petcock install. There's also a strange scratchmark at the mount tab, the exposed metal area doesn't seem to show factory primer the same as I've seen before.
The roughness around the corner recesses and tank surface alongside the opening reminds me of the fuel/corrosion surfaces I ran into when prepping my tank.
Can't quite put my finger on it, but something doesn't look right with the pinstripe masking termination area.
Pinstriping looks a little off, at the right front.
I suppose one could carefully/precisely measure the pinstripe widths, see if they closely match metric, or english widths.
The topside of the tank has very slight surface undulations.
Also, seeing more orange-peel and less gloss than I recall of the period candys.
The front mount nubs are missing some paint, no evidence of exposed factory primer/sealer basecoat.
Yeah, picky, picky, picky.
Probably shot myself in the foot...