The lever with all the holes in it should be connected to the governor.
When you pull the lever to close the throttle with the engine turned off , it should spring back to open the throttle fully.
When the engine is running if you push it to open the throttle it should spring back to close the throttle and maintain 3600
According to the L head manual, the carb is hooked up correctly so that only leaves the governor.
Like Beau I have never worked on on of these engines so do not know exactly what the governor looks like and how to set it.
According to the cross refference charts 143.011004 ( Craftsman number ) is the code for a TVM220-157285H Tecumseh engine
SO the manual for your engine is
TECUMSEH-SERVICE--REPAIR-MANUAL-3HP-TO-11HP-4-CYCLE-L-HEAD-FLAT-HEAD-ENGINES-69250..>
found on this page
http://www.mymowerparts.com/pdf/Tecumseh-Service-and-Repair-Manuals/
Without the engine sitting in front of me the manual makes little sense, but as it is free you may as well download it
The parts breakdown is here
https://az417944.vo.msecnd.net/diagrams/manufacturer/tecumseh/4-cycle-vertical/tvm220/tvm220-157285h/engine-parts-list-1/diagram.gif
In the diagram shaft # 15 should rotate in a clockwise direction as the engine increases speed to slow it down to the desired speed.
As such at stand still the shaft should be as far counter clockwise as it can go and the lever part No # 16 should be holding the throttle butterfly full open.
It looks like it is adjusted via the clamp, part no 17 & 35.
Note the diagram shows the original governor arm and the engine you have has a universal governor shaft with multiple holes for changing the governed speed.
If the shaft # 15 does not move after you have adjusted it then chances are the governor is broken inside the engine.