Yes, you have Zenith carbs. I wanted to wait until I checked mine (and my box of spares) to be sure. Some (not all) of my jets are also stamped "Solex". Here are the numbers that the standard carbs had when new:
Main metering jets: x115
Air Corrector (the brass tube sticking up)
I agree, if you can stand the cash bite go with the Webers.
Hang in there - let me know if you need anything else.
Dan Taylor/ Tulsa, OK MBCA '71 250C/'81 300TD-T