Take a step backwards.
What caused the pushrod to break ?
If it was not simply wearing through at the support then was the problem diagnosed & corrected ?
Do both the valves sit at the same heights when fully closed ?
If not the head has overheated and the valve guide shifted and along with this the valve seat could also be loose and causing sealing problems.
I like to do an in line spark tester & starting fluid test to non starters thus you halve the area of concern .
Otherwise you start at one end and check everything, compression, leak down, fuel flow, valve timing, spark timing etc etc etc
the carb number that you list is invalid. If that is the number stamped into the carb, it is only used for factory use and sometimes for identifying carb kits sometimes. the part number for the carb on your engine is 590430 if before date code 08110500 and 593433 for date code after 08110600 they list for $95.00 the carb repair kit is 796184 which list for $50
