One of our guys bought one and said it needed $200 in body work before it was ready for paint. Original dented rusty tanks have been selling for about $300 on fleabay, but I'm sure the body work would cost a lot more than $200.
BTW, you can buy the Pakistan tanks from most Norton parts dealers, not just the ebay merchant.
If you're building a bike for show it wouldn't be the best choice as I'm sure the judges would notice the differences and dock points. Might be a good choice for a rider though.
I still haven't seen one in person however...
Debby