I purchased an "nos" carb return spring for my rebuild. It has a loop at one end and is straight at the other. I assume the loop attaches at the carb linkage but where is the other end attached? As I recall, when I disassembled the engine, it was attached to one of the exhaust pipe bolts.
Thanks

One end of the spring goes to the throttle rod where it connects onto the throttle shaft on the carburetor. The other end of the spring attaches to the front exhaust pipe flange stud.

You have it backwards. The loop slips over the exhaust manifold stud and the other end to the end of the foot pedal shaft.