The 330hp rating is for a '71 model Boss 351. It had a solid lifter camshaft and valve train, closed chamber 4v high compression heads.
To my knowledge there were never any US Panteras built with it.
The 265hp version is the 4v is in 72 and up US version cars with the open chamber 4v heads, hydraulic lifter cam.
Some of the early magazine specifications are inaccurate.
There may be a Euro only factory spec sheet or brochure with the 330hp mentioned? Technically you could get whatever you wanted in Europe built for you but as far as I know, not on a US delivered version car.