I figured it out. The carb kit comes with a float needle and seating assembly, plus two washers a thick one and a thin one.
They looked the same except for the thickness. I replaced the washer from the kit with the same size washer that i removed, and it leaked. I realized in my sleep last night, maybe the second washer was to adjust the float needle and seating assembly down so that the float would shut off the gas sooner and lower the gas level in the bowl.
I pulled it apart again, installed the second washer, put it all back together again and voila no more leak and the tractor still starts and runs.
Wow, wish there were some instructions with these things.