Help with 706 carb

[brookins]

I have a Farmall 706 (just bought) that seems to have carb problems. The tractor had been sitting all winter; may have had some old gas in it. It sputtered and died while discing. I could start it and get it to move with the choke out but it quits when the choke is pushed in. A friend thought I had a sticky needle.
Questions: Is that likely? If so how do I fix it? Am I looking at a carb re-build? Should I run premium gas in this? Do I need some sort of "lead" additive in the gas?

Thanks.

Brad