I say unusual because i've not seen a serial number like that before with what looks like initials, could it be a ex team bike 

https://www.ebay.co.uk/itm/266422410370
Isn't that a bit steep for a zaskar?
Were some of the 1991 ones stamped 6061? All the ones I have seen didn't have the 6061 stamp, so I had wondered whether that was introduced a little later, but it could have just been inconsistency early on.Even steeper for a 92 pantera in a Zaskar frock
I’d want to see that up close before making judgement any direction for sure as you can tell the difference when you’ve handled enough but the rules all point towards pantera.
I’m on my phone but it would need a 6061 stamp to contradict that. Which was likely a 7005 one that’s been removed as they all are.
Yes could be a team bike but they usually had a different layout too.
I’ve seen both stamped 6061 and not stamped on 91.