1 1/8" lower pins are for Cat II hitches generally found on tractors close to 50 Horsepower and up.
For a Farmall C I'd be setting it up for a Catagory 1 hitch - lower pins are 7/8". Cat I hitches are for tractors under 40 Horsepower - your Farmall C plus most compact and subcompact tractors.
You'll find that Cat i implements are far more common and they match the weight and HP of your tractor. If you do find a light weight cat II implement you want (assuming your tractor can lift it) just change out the lower pins to cat I pins.
Cost of the bit alone will to cut 1 1/8" will run you $60 or $70. You could buy a cat 1 drawbar from northern tool for $30 and use the bit's you have. The drawbar will be half the cost of buying a bit and a better fit for your tractor.