The original owner, who sold it to me, said the cabinet had never even been cracked open. So I would be surprised if it's not the fabric that came with it.
The head's inspection date is 11-25-70 so he must have bought it at year's end or very early 1971.
I suppose anything's possible, it certainly wouldn't be the
first Sunn "head scratcher" I've run across. Hopefully those factory oddities will add to their value once the vintage gear crowd finally realizes what gem's the old Sunns truly are!
However, this is why I suspect that the grill on your amp has been changed;
First, as we have established the grill cloth is unlike any that myself, or so far anyone
else on this site has seen.
Secondly, in the picture it looks like the grill cloth is crooked; the horizontal lines are wavy relative to the Sunn logo. Especially when you look at the '71 in your pic, or the Sceptre in my pic, or for that matter
any factory grill cloths I've seen up close.
I wish I could say the same about my
personal recovering efforts.
Third, the frayed corner doesn't look like the corner on a factory job. Even the factory grills I have that have been removed repeatedly stay together in the corners; again my recovers on the other hand often fray like the one you pictured.
Even if it
is a recover, that doesn't change the fact that you have got a world class "score" on your hands. $400 for a super clean matching 200S rig? Heck, I'll give you $450 for sight unseen!
Maybe we'll get lucky and Conrad will chime in and resolve this quandary...