Pictures of the calipers? The Turbo S used larger calipers in the front and the same calipers as the regular 944 Turbo in the rear. It depends what calipers you got.
Your '85.5 will require early offset rotors from an '86 944 Turbo. Also you will need '86 turbo Spindles and hubs (not sure about the hubs, you may be able to reuse your old ones).
The rear calipers bolt right up, but you need the correct rotors.
There are a few other mundane things like different length bolts.. but you can worry about that after you figure out what you need.
Caliper on the left is a regular 944 Turbo caliper, they look the same front and rear, though the piston sizes are different. On the right is a Turbo S front caliper.
Based on your description, i bet he sold you the rear calipers.