Thats too bad about missing parts, I've had good luck with an aftermarket starter and carburetor that I got from yesterdays tractor about eight years ago, for my ford 8n. Or you can rebuild what you have, I know many guys prefer the carburetor rebuild kits from case ih if you have a dealer close. Napa sells some things for it also, or at least used to a few years ago. The brand new tires are big plus.
I got tired of fighting the rust flakes and junk in the gas tank on my 1945 h and removed the tank and rinsed it out, no problems since.
We had a cub for a few years then sold it off for a IH 184 low boy. I believe that the tractors share the same engine, but the 184 is a big lawn mower and the cub is a capable tractor. The cub has better gearing, pto and hydraulics.
I miss the cub, it was pretty nice hauling wood and it did pretty well with a woods belly mower out in the pastures from what I remember. I'll probably get another one if I come across a good deal.
Best of luck with yours