There is no way to tell what you really have: the engine looks to be a hodge-podge of parts. Just by the picture, you have a fuel pump meant for a motor with an altenator (canted away from the generator to make room for a larger diameter altenator), what looks to be an 009 distributor, after-market dual carbs (
AFAIK dual ports only came with a center-mounted single barrel Solex, witness the block-off plates on the exhaust heat risers), an electric fuel pump hot-wired to the coil (which is dangerous in the event of accident - needs an inertia switch). If the case has two mount points either side of the pully/oil pump, it is most likely a universal replacement case used for either Type I motors or Type II with rear mount. With the motor hard-mounted to the chassis, the mount and/or mount points will eventually fail due to vibration. You also have a throttle cable; 912 linkage is all rod with ball joints and bell cranks (one on the transmission near the nose and one on the back of the fan shroud).
A popular upgrade to dual port motors were big bore kits from 87mm to 92mm depending on slip-in or machine work (85.5 was stock for the 1600): no way to tell by looking.