That looks right, heres one of my carbs.
I did notice the rubber on mine was rock hard and is due for replacement.
One thing to look at would be the fuel filter, even if its been replaced. If blocked it may not be supplying enough fuel and the choke may be making the reduced amount just rich enough for the engine to run.
Theres also a filter in the carb and in the tank, pull the line off past the fuel pump and see if the tank filter is flowing too.
Either way, you're right, by now the carb would benefit from a clean and kit, pretty easy to do yourself.
Theres also lots of scope to increase performance, if you're running a sports filter you can easily up the main jet from 130 to 135/137 with the increased airflow.
Depending on how serious you want to get, some airhorns will also be a benefit, a couple of examples
https://www.pegasusautoracing.com/pr...asp?RecId=1254
https://www.pegasusautoracing.com/pr...sp?RecID=31519
This article has some interesting ideas for achieving maximum performance
http://www.thelolaregistry.com/DIY/Weber.htm