It looks as if the mountings are simply WRONG.
'53 Frame featured a brazed on prop stand lug and a rubber mounted thro' sleeve at the front, to take the tank mounting bolt. This tank has a slotted front mount. At the rear, the tank mounts themselves are rubber bushed, with a through bolt going through the frame lug. This is hardly likely to be reproduced for today's market. A bit of make do and mend seems to be par for the course with a lot of these tanks.
That tank is lying too low at the front, and should be closer to the steering head. Plenty of pictures on the web. Moving the tank forward will solve the seat problem.
As for buying an Indian Tank, for UK buyers there are now a good few UK dealers, and with the variable quality, getting some sort of redress for a wrong'un is far easier than trying to get sense out of some outfit halfway around the world. They may cost a bit more, but you'll sleep easier...
Swarfy.