A 74+ tank will not fit - the 74+ tank is basically a 240 tank, and the floorpan in that area of a 74+ car is completely different. The boot panels are different shapes, including the panel behind the rear seat backrest.
The 1213748-5 tank also went into the pre-74 164Es.
You can always solder up the damaged tank, after suitably ensuring there isn't any remaining flammable fuel vapor in the tank before you begin work. (Just filling the tank with water does not work).