701 carb and wheel question

[sodbuster 1]

finally started working on my 701.when I tore down the carb I found a spring where the needle and seat are.Is this something the factory did back in 1961?? it appears to be factory,the spring has a beveled cap on one end to stop fuel.

 

  wheel question: what size are the front wheels,I need one front. bore size,width etc... thanks

 

update: before tearing carb down,I was curious if the tractor would run.after setting 25 plus years. installed battery,hot wired it,(key is broke off in ignition) changed plug ( had a weedeater plug installed) shot some go go juice in her,she rooled over about three times,and fired up!!! with a little work I am going to make this my mowing tractor!